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PRELIMINARY FILE FOR M.I.D.I. DICTIONARY c.A.C.CONTI 1986,1987 AC (ALTERNATING CURRENT)-A flow of electricity which reaches a maximum value in one polarity,decreases to zero,reverses, then reaches a maximum value in the opposite polarity.(compare DC) ACIA- Asyncronous Communications Interface Adapter.A device which enables the parallel output of a computer to be converted to serial output.(see UART) ACTIVE SENSING-A method by which an instrument or other piece of equipment detects disconnection.A message is sent to the receiver every 300 ms.If no message is received in a 300 ms period,the unit assumes the MIDI connection has been broken, and a routine to reestablish normal operation must be implemented. ADSR-Attack Decay Sustain Release.-four parameters for synthesizing sounds.The basic sound envelope consists of four elements or parameters which determine the final sound as it changes over time.(see specific entries) AFTER TOUCH-(KEY PRESSURE)(CHANNEL PRESSURE)the maintainance of keyboard pressure after the keys have been struck.In MIDI, this is a teo or three byte channel voice message.(see SUSTAIN) AFTER TOUCH COMMANDS -A channel voice message, of either two or three bytes.A two byte command of the form (1) 1101nnnn (&HD w/ channel number ) (2) 0vvvvvvv (pressure value) will control the pressure for a specific channel.A three byte command of the form (1) 1010nnnn (&HA w/channel number) (2) 0kkkkkkk (key number) (3) 0vvvvvvv (pressure value) will control pressure for each key. ALGORITHM- A method of solving a problem.A procedure that will, if followed,provide a solution to a problem. ALL NOTES OFF- A three byte MIDI channel mode message which can turn off all notes which have been previously turned on via MIDI,of the form (1) 1011nnnn (&HB w/ channel number) (2) 0111 1001 (&H7B) (3) 00000000 (&H0-zero velocity data) ALIASING (FOLD-OVER)-The result of sampling frequencies greater than one-half the sampling rate. In the digitization of such a signal, a false or ALIAS signal is created from the sampled data,then, when outputted, a false signal within the system's bandwith is heard. AMPERSAND-"&"-the `and' symbol, used to designate a hexadecimal number when used before the number. Example &h10 is equivelent to decimal 16. AMPLIFIER (AMPLIFICATION)-a device which causes the ratio of output to input magnitude of a signal to increase.The output signal is a reproduction of the input signal except for an increase in voltage current or power. AMPLITUDE-The magnitude of any changing quantity when compared to its `at rest' or `zero' value. ANALOG- information about the world which is a direct and proportionate analogy of actual physical occurences.(compare DIGITAL) ANALOG SYNTHESIS- utilization of waveforms to create various sounds varying through time.The shape of the wave,the harmonics of the wave and the ADSR (which see) times will effect the resultant sound.A direct electrical model of an accoustic sound generator is created by an analog synthesizer.The analog oscillator will model a vibrating string or a column of air..A analog filter will model resonances like a sound board in a piano, or the shape of a violin.(Compare DIGITAL SYTHESIS) ARPEGGIATE-to play the notes of a chord is succession rather than simultaniously ASCII- The American Standard Code for Information Interchange.A seven bit code also known as the the USA Standard Code for information Interchange (USACII).Because eight bit codes are more common on computers, ASCII is normally imbeded in an eight bit(one byte) code.This code provides 128 possible combinations whereby control characters and graphic characters can be encoded in digital representation. ATTACK-one of the four basic sound parameters,it is the measure of time from the initial initiation of the sound to its highest or maximum level. AUTO-CORRECTION-(SEE QUANTIZATION) BAUD -The rate per second at which bits of computer information are transmitted or received. For MIDI, this rate is 31.25 Kbaud (31250 bits per second.) Note, although for MIDI, one bit is sent per baud, higher and lower bit rates can exist. BENDER- A lever or wheel on musical instruments which will change the pitch of all notes being played.Bender information is a three byte channel voice message of the form; (1) (STATUS byte) 1110nnnn ( &HE and the channel number) (2) (DATA byte) 0vvvvvvv (low end of range), (3) (DATA byte) 0vvvvvvv (high end of range). BINARY NUMBERS-A base 2 numbering system in which each digit, instead of being 0 to 9 as in the decimal system, is either a 0 or a 1,(on or off).see HEXADECIMAL. BITS(BYTES)- Computer mode of information expression composed of `ones' and `zeros'.One bit equqls a `one' or a `zero'. Usually 8 bits=1 byte, however, MIDI uses a 10 bit-byte, sending a start bit,("0"="L"), the 8 bit data, and a stop bit,("1"= "H"). BUFFER- an area or device for the temperary storage of data. CHANNELS-(CHANNEL COMMANDS) (channel messages) there are 16 discrete channels assigned to MIDI commands. Channel messages include both VOICE messages and MODE messages. Channel Voice Messages carry data which control the tones(pitch) and channel number, and can include such data as NOTE ON,NOTE OFF, AFTER TOUCH, BENDER,CONTROL CHANGES, AND PROGRAM(PATCH)CHANGES. For example , a channel voice message is composed of three bytes. The first byte is called the `STATUS' byte(which see), the second byte (DATA byte) indicates what `key' is to be sounded(pitch),the third byte (DATA byte) indicates the velocity (which see). Channel Mode messages include OMNI ON/OFF, MONO, POLY, ALL NOTE OFF,LOCAL ON/OFF(SEE MODE) CHORUSing- an effect whereby an sound can be made to sound like an entire ensemble.The initial signal is split a various number of times, delayed slightly and then the delay time and level are modulated by the Low frequency oscillator.(LFO) CONTROLLERS- equipment such as levers, handles, or buttons that allow variation of data through the range of the controller.Examples are joysticks, benders, potentiometers,etc. CUT-AND-PASTE- a function of sequencer software where one section of a piece of music can be ammended or replaced with another piece of music.(see SEQUENCER). DATA- any kind of information.Itis the content of a MIDI message, defined by the MIDI status byte.(see STATUS BYTE) DECEBELS-Db'S-(FROM BEL-named for Alexander Graham Bell) a Db is 1/10th of a bel. It is the measure of relative sound strength when comparing two signals. This ratio is logarithmic; i.e. 20db= a factor of 10 in voltage change. DC-(DIRECT CURRENT)-A current of electricity which always flows in one direction. A battery delivers this type of current. (compare AC). DECAY- One of the four basic parameters of sound synthesis. Itis the component parameter measured from the point of greatest level to the point of sustain. DEFAULT- A preprogramed or preestablished condition to which a command will be initialized, usually called `power up' settings. Also,in the absence of the ability to accept certain kinds of data (see velocity), the machine will `default' to a certain value. DELAY-The time difference between the arrival of the direct sound and the first reflection to reach the listeners' ears. Usually measured in milliseconds, with 1000 milliseconds equal to one second. Human perception of delay occurs around 30 milliseconds. DIGITAL -symbolic representation of physical information by using fixed voltage levels to represent information in numeric code.The binary representation of digital information is in ones and zeros. (compare ANALOG) DIGITAL SYNTHESIS(DWS)- the representation and generation of waveforms by the use of streams of numbers. Each digital number represents a particular point in time of the represented waveform.The numbers represent samples of the waveforms.The digital signal is discrete in time and in amplitude.+ DIN PLUG-a five pin female plug.In MIDI, only three of the five are used.Pins 1 and 3 are not used. DISTORTION-Any change in the waveform of a signal resulting in abnormal sound qualities DRUM MACHINE-an electronic device which allows the creation of percussive sounds and patterns. DYNAMICS-the relative loudness or softness of a piece of music. ECHO-The repetition of a sound delayed in time. ENCODING- conversion of analog information into digital information, ones and zeros, which represent quantized values. ENVELOPE- the total variation of a sound over time. Envelope descriptions usually follow the ADSR( attack,decay,sustain,re- lease)format.An envelope represents the changes of pitch, volume and timbre, over time.(see specific entries) EQUALIZATION-(E.Q.) The boosting or cutting of various frequen- cies by amplitude adjustment. EVENT-a musical data message consisting of one or more bytes. Execution of a routine that performs an output action: (SEE MESSAGES or system messages) EXCLUSIVES -SEE SYSTEM EXCLUSIVE MESSAGES. FILTER- a circuit which permits certain frequencies to `pass' easily while inhibiting or preventing other frequencies from passing.For example,a low pass filter (LPF) only allows low frequencies to continue through the circuit. FREQUENCY- the rate per second at which an oscillating material completes one cycle.Usually measured in HERTZ.(Hz) For example, a sound at 440 Hz, completes one cycle of air oscillation 440 times per second. FSK-FREQUENCY SHIFT KEYING.In order to send or store digital data in an audio format, the audio tone will shift between two frequencies,differentiating ones and zeros.Can be used for start and stop syncronization (SEE TIMING OR MIDICLOCK). HERTZ- a unit of electromagnetic wave frequency equal to one cylce per second. Named after Heinrich R. Hertz. HEXADECIMAL(HEX)- A counting system using 16 as its base.The decimal system uses 10 and the binary system uses 2 as their bases. It is a convenient way to represent binary numbers to a computer.In order to alert the reader that hex symbols are being used, the letter H will follow the number,or the symbol `&' (ampersand) and `h' will appear before the number. Binary Value Decimal Value Hex Value 0000 0 0 0001 1 1 0010 2 2 0011 3 3 0100 4 4 0101 5 5 0110 6 6 0111 7 7 1000 8 8 1001 9 9 1010 10 (&h) A (H) 1011 11 B 1100 12 C 1101 13 D 1110 14 E 1111 15 F INTERFACE -a device or method where two or more machines, instruments or processes are enabled to cooperate. Examples includes UARTs, buffers, I/O devices,software and hardware. JOYSTICK CONTROLLER-(SEE CONTROLLERS) KEY-a note sounded, or specified. In a composition, the most frequently used pitch, around which the other notes are related. In a MIDI channel voice message, the key number data is contained in the second byte of a note on command. When this key data is received by the instrument, the corresponding note on the keyboard sounds. KEY SPLIT- a configuration of a keyboard where, from acentral key, all the sounds downward are of one patch, all of the sounds upward are of another. LCD- Liquid Crystal Display. Frequently used on instruments to display the data. LOCAL ON/OFF-a three byte channel mode message of the form; (1) (STATUS byte) 1011nnnn ( &HB then the channel number) (2) (DATA byte) 0ccccccc (ccccccc=122 equals local control) (3) (DATA byte) 0vvvvvvv (if vvvvvvv=0 then local control off, if vvvvvvv=127 then local control on. If LOCAL ON is sent, the receiver is able to produce sounds from the MIDI data and the keyboard.If LOCAL OFF is sent, only MIDI data is accepted, the keyboard is disabled. LOOPS-SEQUENCER LOOPS- the repetition of a particular pattern. In sequencers, the beginning and ending of a phrase can usually be specified. In sampling, the point in a sound envelope when the sample returns to the beginning (ATTACK) of the sound, or to the SUSTAIN portion of the envelope. MEMORY-the amount of available space for digital information or events. Memory is usually expressed in Kbytes. That is 64k means 64000 bytes of memory are available. In general, there are two kinds of computer memory, ROM (read only memory), and RAM (random access memory). ROM memory can only be read by the computer and the data is usually not able to be altered by the user. RAM memory, is the memory that is user-accessable and the data can be altered through programs. MERGING-the combining of one set of data with another.(see midi merge) MESSAGES- one or more bytes of data.Another term for an event.Any MIDI information sent over the MIDI bus.Catagories include Chan nel messages,voice messages,mode messages,system exclusive,system common, and system real time messages.(see specific entries) METRONOME-a device or method providing a discrete pulse.Used for a rhythmic continuity. Click tracks,pulse codes, timing clocks can all provide metronomic pulses. M.I.D.I. - An acronym for Musical Instrument Digital Interface. An international standard which facilitates communication and intercommunication ofperformance data by means of digital signals. Enables communication between equipment from different manufacturers. MIDI CLOCK-a system real time message (which see) over the MIDI bus to enable the synchronization of other equipment such as sequencers, drum machines, or other keyboards. The usual rate is 24 divisions per beat, but can be configured on some equipment into 48 or 96 divisions per beat (see quantization). MIDI IN, OUT AND THRU.The female DIN connector through which the MIDI IN receives the MIDI signal. MIDI OUT transmits the MIDI signal through a female DIN connector. The MIDI THRU provides an exact (transparent) electrical copy of the signal coming into a device via the MIDI IN, however approx. a 10 millisecond delay is introduced. MIDI MERGE- the combining of MIDI data from one or more sources into one source, usually with the ability to later seperate the data later into its constituant parts. MIDI PATCHER-A device to allow various configurations and reconfiguration of MIDI equipment,keyboards, drum machines,etc.(see networking) MILlISECOND- (ms) One thousanth of a second,(see DELAY) MODE-a three byte MIDI message which determines the information that a receiver will receive regarding channel data and voice (note) data, of the form; (1) (STATUS byte) 1011nnnn (&HB then the channel number), (2) (DATA byte) 0ccccccc (ccccccc=Type of control), (3) (DATA byte) 0vvvvvvv (vvvvvvv=number of channels). There are four possible modes in MIDI: MODE 1-OMNI ON POLY ON In this mode,voice messages are sent on the basic channel,and received from all channels,then assigned to voices polyphonically MODE 2-OMNI ON,MONO ON(POLY OFF) In this mode, voice messages are received from all channels, and are assigned to control only one voice,monophonically. MODE 3-OMNI OFF, POLY ON In this mode, voices only in the basic channel number(n) are received, and are assigned to voices polyphonically Voices without the basic channel number are ignored. MODE 4-OMNI OFF,MONO ON(POLY OFF) In this mode, voices are received on the basic channel and channels upward to the limit of the particular instrument. That is, if an instrument contains eight channel receive capability, the incoming voices are received on the basic channel(n) through n+7 inclusively, then assigned to voices one through eight, respectively.The number of voices is specified in the third byte of the mono mode message. Mode messages also include ALL NOTE OFF, and LOCAL ON/OFF(WHICH SEE) MODULATION -a periodic change in sound.Can be the a trill or vibrato, a swell, or attack. Can also be the motion of a piece of music from one key to another. MONOPHONIC- a single sound source or note.A devive which can generate only one sound at a time.The UNISON setting outputs a monophonic sound.(COMPARE POLYPHONIC) NETWORKING-Linking various MIDI devices together in order to share or exchange information, or performance data. SOME LINKING SCHEMES (1) UNIDIRECTIONAL- Masterto Slave, MIDI OUT OF A IS CONNECTED MIDI IN OF B (2) BIDIRECTIONAL- Two masters interchange functions MIDI OUT OF A IS CONNECTED TO MIDI IN OF B, MIDI OUT OF B IS CONNECTED TO MIDI IN OF A. (3) DAISY CHAIN-One master drives several slaves using MIDI Thru,however delays (howmuch?)will occur in performance.MIDI OUT OF A CONNECTED TO MIDI IN OF B,MIDI THRU OF B CONNECTED TO MIDI IN OF C, MIDI THRU OF C CONNECTED TO MIDI IN OF D,ETC (4) RING-EXTENSION OF BIDIRECTIONALITY CONNECTING THREE OR MORE DEVICES.MIDI OUT OF A TO MIDI IN OF B,MIDI OUT OF B TO MIDI IN OF C.MIDI OUT OF X CONNECTED TO MIDI IN OF A (5)STAR- MASTER UNIT HAS SEVERAL UNIDIRECTIONAL AND/OR BIDIRECTIONAL LINKS NOTE COMMANDS- a channel voice message usually referring to a particular note to be sounded. A three byte message of the form; (1) (STATUS byte) 1001 nnnn (&H9 then the channel number), (2) (DATA byte) 0kkkkkkk. This is the key number of the note to be sounded (0011 1100=60 which is middle C), (3) (DATA byte) 0vvvvvvvv. The velocity or loudness of the note.(0000 0001 is the softest, 0111 1111 is the loudest.) OHM(OHM'S LAW)- a measure of electrical resistance.Ohm's Law states that V=IR, where V is the voltage across a resistor in volts,I is the current produced in amperes,R is the resistance measured in Ohms. OPTO-ISOLATOR-a device in a MIDI circuit which converts the input signal into a data stream that a MIDI device can utilize. This is an electrically isolated switch; the input side,(an LED-Light Emmitting Diode) will turn on a transistor (the switch) with light. This keeps the devices electrically seperated in order to minimize noise and grounding interference.Examples include, a Sharp PC-900 or HP 6N138. Sould require less than 5mA to turn on, and a rise and fall time less than 2 microseconds. OSCILLATOR-a circuit,device or program that generates an alterna- ting or pulsating current,waveform,or numerical values. PAN- the moving of a singal from the left area of perception to the right, or vice-versa. PARAMETERS- elements of sound synthesis which determines the conture, limits or distinguishing characteristics of a sound, sound source, software, or any piece of equipment. PATCHES-programs, timbres, or voices. Thse are the sounds that can be generated by a particular piece of equipment or software, and are usually locatable and referenced under one number which can be recalled and outputted. PITCH-a continuous frequency over time. PITCH BEND- The variation, by means of a bender or controller, off the initial pitch, either up or down.(see BENDER) POLYPHONIC-multiple sounds.A keyboard is said to be polyphonic if simultanious sounds can be generated.(COMPARE MONOPHONIC) PORTS(SERIAL, PARALLEL)- The recieving and transmitting areas of a computer. POTENTIOMETER-a variable resistor used to change or divide voltage.( called a pot) PRESETS-settings provided by the manufacturers which incorporate features the manufacturer feels are useful to the user. These can include patches, programs, loop lengsths, default values, etc. PROGRAMS (SEE PATCHES)-a program relative to a computer is a set of commands which control the operation of the computer. A program in MIDI refers to a two byte message sent when a patch (timbre) change is desired. A program change command is a channel voice message of the form; (1) (STATUS byte) 1100nnnn (&HC then the channel number. (2) (DATA byte) 0ppppppp (ppppppp= the program number). QUANTIZATION-(auto-correction) Whenever a measurement is rounded or truncated to the nearest whole or quantum value.In most sequencers, this allows adjustment of recorded material to be performed precisely on a selected division of the beat,(usually up to 96 divisions per quarter note). REAL TIME- Actual time as it occurs, includes recording MIDI information in a manner similar to analog tape recording. For example, by performing a piece of music on a MIDI keyboard, a sequencer will store the data for later playback, exactly as it was performed, within the specified quantization limits.(compare STEP TIME) REAL TIME MESSAGES- System real time messages are for syncronizing all of a MIDI system in real time.(see SYSTEM REAL TIME COMMANDS) RELEASE- One of the four basic parameters of sound synthesis. It is a measure of the length of time for the envelope of a sound to go from the sustain level to zero. RESONANCE- (resonance frequency) An increase in sound intensity caused by the amplification of a DC voltage ,or the addition of original and reflected sound waves. Resonance frequency is the frequency at which something will sympathetically vibrate with the original signal. REVERBERATION -the result of myriad reflected sound waves in an accoustical environment.(COMPARE DELAY/ECHO) SAMPLING- digitizing a waveform by measuring the waveform's level at precisely timed intervals, then converting these measurements into one's and zeros. Usually accomplished by an A to D (analog to digital) coverter. What levels and at what time intervals the wave is sampled determine the sampling scheme and the SAMPLING RATE. SAMPLING RATE- The rate at which samples are taken of a waveform. Sampling theory suggests the Nyquist rate be the minimum rate of sampling. This is equal to twice the highest frequency to be represented. The Nyquist frequency is the highest frequency that can be represented by a digital signal. It is equal to one-half the sampling rate. SEQUENCER-a software or hardware device which is analogous to a tape recorder, in that sounds are stored and can later be replayed. Major differences are that a sequencer usually allows QUANTIZATION of performance, the ability to MERGE various data tracks, a CUT-AND-PASTE option, an ability to accelerate or decellerate a piece of music without changing the PITCH, an ability to TRANSPOSE a piece of music without changing its speed, the ability to enter data either through REAL TIME performance or STEP TIME performance,and many other options which will vary with manufacturers. SMPTE CODE-(Society of Motion Picture and Television Engineers. (TIME CODES ( MIDI CLOCK) AND SYNC CLOCKS SONG POSITION POINTER- A SYSTEM COMMON MESSAGE which is an internal register which holds the number of MIDI beats (1 MIDI beat= 6 MIDI clocks) since the start of a song. Normally, this register is set to 0 when a start switch is pressed, which starts sequence playback. It continues to increment until stop is pressed. It can be arbitrarily preset, to a higher resolution, by the SONG POSITION POINTER message.The message is off the form; (1) (STATUS byte) 11110010 (&HF2) (2) DATA 0lllllll (lllllll=LS) (3) 0hhhhhhh (hhhhhhh= MS) SONG SELECT- A SYSTEM COMMON MESSAGE which specifies which song or sequence is to be played upon receipt of a start (REAL TIME) message. A two byte message of the form (1) (STATUS) 11110011 (&hF3) (2) (DATA) )sssssss (sssssss=song number) SPLITS-an option whereby upper and lower ranges of the keyboard can be asigned different timbres. STATUS BYTE- Defines what MIDI data the message carries.For instance, in a NOTE ON command, the first four bits of the status byte will indicate that a pitch is to be sounded, the second four bits will determine the channel number. STEP TIME:the recording of notes by individually specifying their pitch and duration. In SEQUENCER software, this means be able to take an individual note specification, match it with a durational specification and store it in the program to be performed in real time. (compare real time) SUSTAIN-one of the four basic parameters of sound synthesis.It is the measure of time from the end of the decay period to the beginning of the release period. SYNC CLOCKS- Algorithms which allow the syncronization of devices. MIDI clocks enable one MIDI device to be syncronized with anoth, FSK syncronization allows external analog tape recorders to syncronize MIDI devices. SMPTE clocks allow the syncronization of MIDI, tape and video or movie film to be syncronized.(VARIOUS SPEEDS & TYPES OF SYNC CODES ???) SYSTEM COMMON MESSAGES- MIDI messages used to activate or record song data, or used to tune a MIDI instrument. Current examples are: SONG POSITION POINTER, SONG SELECT,TUNE REQUEST, EOX. SYSTEM EXCLUSIVE MESSAGES(SYSTEM COMMANDS)-UNIQUE messages of a particular manufacturer.Can be used for specific purposes such a sending sequencer data, bult patch information, parameter information,etc.Each MIDI equipment manufacturer has a unique ID. This ID number can be obtained from the MIDI committe.Format is (1) status byte (F0H),(2) manufacturers Identification Number(ID),(3)Command(usually three bytes but can vary per manufacturer),(4) End of system exclusive(F7H) Some manufacturer ID's are: HEX Sequential Circuits 01 Big Briar 02 Octave Plateau 03 Passport Designs 05 Kurtzweil 07 Oberheim 10 Roland 41 Korg 42 Yamaha 43 Casio 44 SYSTEM REAL TIME MESSAGES-commands which communicate timing information which is used to synchronize one MIDI device with another. TIMBRE- that element of sound which distinguishes one sound source from another.A difference in waveform will cause a differ- ence in timbre TIME CODE In video, a method of identifing each frame by an eight digit format:hours;minutes;seconds;frame. for ex. 00;05;14;26 means the 26th frame located 5 minutes and 14 seconds into the piece. TRANSPOSE-raising or lower a sequence of notes by a fixed value.For instance to change a melody in C to D, 2 can be added to each note number and the melody is transposed. TREMELO-a rapid alternation of two tones. Usually a third apart. On a synthesizer, this effect can usually be controlled by the modulation wheel or modulation amount. TUNE REQUEST- A SYSTEM COMMON MESSAGE used with analog synthesizers to request that they tune their oscillators. It is a one byte STATUS request of the form, (1) (STATUS) 11110110 (&HF6) with no data. U.A.R.T.(Universal Asynchronous receiver/transmitter).Used by MIDI interface to convert parallel data formats to serial data formats and vice versa.(see also ACIA).This device is used to carry out parallel to serial and serial to parallel conversions. Usually a single chip that also controls transmission rate(baud rate), generates start and stop bits, and provide other control functions involved in interfacing. VELOCITY-determines the characteristics of decay(NOTE OFF) or attack,(NOTE ON).Describes a level of loudness (`hardness') of key striking. Some machines do not recognize velocity information and therefore default(which see) to a value of 64 VOICES-(SEE PATCHES) VOLTAGE- A UNIT OF ELECTRICAL PRESSURE MEASURED BETWEEN ANY TWO POINTS IN A CIRCUIT.One volt is the amount of pressure needed to force one ampere of current through a resistance of one ohm WAVEFORM- The shape of a vibrating body of air when viewed on an oscilliscope.There are three basic waveforms,sine-wave,saw-tooth, and squarewave, used in sound synthesis, although Fourier analysis enables virtual any waveform to be generated from the addition of simple sinewaves with various frequencies and amplitudes