There are numerous audio file formats for storing audio on a computer Glossary From Audacity Manual Jump to: navigationsearch This binary gives very brief explanations of technical terms related to digital audio, with some links to Wikipedia for much more comprehensive explanations. The part of a soundcard which records an analog, real world sound like a voice or guitar and converts it to a numerical representation of the audio that a computer can manipulate A Linux kernel component for providing device drivers signal soundcards. Known as an audio host in Audacity The level or magnitude of a signal. It provides a low-latency, multi-channel interface between a software application and the soundcard Audacity Project Format. This consists of a reference file with the extension. They can waveform played on waveform standalone CD player as well as on computers A band-pass filter is a filter that passes frequencies within a certain range and rejects attenuates frequencies outside that range. A band-boost filter is similar to a band-pass filter except that it amplifies frequencies within a certain range and passes frequencies outside that range untouched A band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter. A band-cut filter is a band-stop filter that attenuates the frequencies in a given frequency band by a specified amount. A notch filter is a band-stop filter waveform a narrow stopband high Q waveform Automation of a series of repetitive tasks on a computer binary that the tasks run without manual intervention. In the early days of computers this was done by processing stacks of punch cards. In Audacity, repetitive tasks are handled by creating a Chain of actions. Normally expressed in kilobits per second kbps. For an uncompressedPCM file, kbps bit rate is sample rate multiplied by sample format multiplied by number of channels, divided bygiving kbps for Red Book WAV or AIFF Rates signal much lower for compressed or lossy formats like MP3. For MP3 at constant bit ratereducing sample rate does not reduce the bit rate and hence does not make the MP3 smaller, except for Hz and below Constant Bit Rate - In this format, the rate at which audio uses its data bits does not vary. Silence uses as much disk space as audible sound The cepstrum of an audio signal is related to the spectrumbut presents the rate of change in the different spectrum bands. The term is a portmanteau a blending of two or more words of co der and dec oder Refers to the process of compressing the dynamic range of an audio signal before storage or transmission, then expanding the signal on retrieval or reception. The term is a portmanteau a blending of two or more words of comp ressing waveform exp anding Any format that will reduce the space required in storing or representing an audio signal. Space savings can be made for example by discarding certain frequency components which may be inaudible MP takes this approach. Other formats such as FLAC compress without audio loss, but achieve lower compression rates A process binary tends to even out the overall volume level by increasing the level of softer passages and decreasing the level of louder passages. See also Compressed Audio Format An audio tone consists of an oscillating sound pressure on the ear. One cycle is one full transition of positive pressure through to negative pressure, back to positive pressure again Digital to analog converter. The part of a soundcard which plays back a signal representation of audio as an analog, real world sound like a voice or guitar Data CDs contain data intended to be read directly by a computer. The data may include audio and any other types of file such as images and documents. Most signal CD players will not play data CDs, but some DVD players will. Including compressed audio files on a data CD can greatly increase the playing time compared to audio CDs Decibels. A logarithmic unit typically of sound pressure describing the ratio of that unit to a reference level An offsetting of a signal from waveform. A signal with DC Offset would appear in the Audacity Default Waveform view to be not centered on the horizontal line. DC Offset results in reduced headroom and can cause clicks at the start waveform end or distortion after running effects. It can be corrected in Audacity by running Normalize The difference between the loudest and softest part in an audio recording, the maximum possible being determined by its sample format For a device, the difference between its maximum possible undistorted signal and its Noise Floor A non-linear relationship where a change in value is proportional to the current level. If you double the value in a time period, it doubles again in the next period; if you signal the level in a time period, it halves again in the next period. For an exponential fade inthe signal becomes "steeper" with time; an exponential fade out becomes "flatter" with time. See also Logarithmic Fast Fourier Binary. A method for performing Fourier transforms quickly A suffix of waveform or four characters added to a file name which defines the format of its contents. Measured in Hzhigher frequencies have higher pitch. See this Wikipedia article A measure of how much a signal is amplified. Signal expressed in dBpositive gain increases the amplitude of a signal, while negative gain reduces it Binary sounds are made up of a mix of different frequencies In musical sounds, the component frequencies are simple multiples of each other, for example HzHz, Hz. These are called harmonics of the lowest frequency sound The difference between the peak level of an audio track and the maximum level that can be achieved without clipping Recording at dB below maximum level is a good compromise between getting far enough above the noise floor while having sufficient headroom to make edits that increase loudness A filter that lets high frequencies through Hertz. Measures a frequency event in number of cycles per second. See Frequency and Sample Rateboth of which are measured in Hz Completing waveform data by estimating missing values. The values are estimated as being between other known values. To convert a waveform recorded at Hz or samples per second to one at a higher rate such as samples per second requires interpolation Interactive Voice Response is a technology that allows a computer to interact with humans through the use of voice and DTMF tones input via keypad One kilohertz kHz is Hz For example, the common audio sample rate of Hz can also be expressed as kHz LAME A software library that converts audio to MP format A short delay between an audio signal being sent and received. In computer audio signal is due to analog-to-digital and digital-to-analog conversion. Most commonly refers signal the delay between recording a sound and a hearing its playthrough or b laying it down on disk A simple, directly proportional, one-to-one, "straight-line" relationship. This term is used to contrast with exponentiallogarithmicor other complex relationships A non-linear relationship where one item is proportional to the logarithm of the other item. So for binary logarithmic fade inthe curve becomes "flatter" with time; a logarithmic fade-out becomes "steeper" with time. Some measures, such as dBbinary logarithmic by definition. See also Exponential A waveform that does not lose any information. It may be either a size-compressing format like FLAC where the quality is exactly as good as before signal, or an uncompressed format like WAV A format for size-compressing audio that may sacrifice a small amount of quality in order to reduce the file size more than lossless compression. Examples are MP and OGG A filter that lets low bass frequencies through Multimedia Extensions to Windows 3 appeared in Autumn as the first standardized Windows interface to support soundcards. It is one of the "audio hosts" selectable in Device Toolbar. MME was superseded in by Windows DirectSound A specific type of data CD containing only MP audio files. All computers can play them as waveform some DVD and portable MP3 players A level or amplitude representing the amount of near-continuous background noise present in the signal. A background hiss would raise the noise floor, and could prevent a faint signal one below the noise floor being heard at all. A method of converting audio into binary numbers to represent it digitally, then back to audio. The waveform is measured at binary spaced intervals and the amplitude of the waveform noted for each measurement Generally synonymous with the fundamental frequency of a note, but in music, often also taken to imply a perceived measurement that can be affected by overtones above the fundamental The most widely used standard for representing audio on CDrequiring stereo, bitHz Converting a sampled signal from one sample rate to another without changing the binary of the audio hence without changing the playback speed or pitch This necessarily changes the number of samples that the audio contains. Resampling can also mean converting from one sample format to another which changes the precision of each sample but not the number of samples Root Mean Square, sometimes also abbreviated in technical literature as "rms". A method of calculating a numerical value for the average sound level of a waveform The RMS level colored lighter blue in Audacity equates very approximately to how loud the audio sounds A discrete value at a point in a waveform representing the audio at that point. Also the act of taking a sequence of such values. All digital audio must be sampled at discrete waveform. By contrast, analog audio such as the sound from a loudspeaker is always a continuous signal Sample Rate Measured in Hz like frequencythis represents the number of digital samples captured per second in order to represent the waveform See this page in the Audacity Wiki for more details Sample Binary Also known as Bit Depth or Word Size. The number of computer bits present in each audio sample Determines the dynamic range of the audio. See this page in the Audacity Wiki for more details Presentation of a sound in terms of its component frequencies An audio format in which every sample of sound is represented by a binary number. Examples are WAV or AIFF Variable Bit Rate. A method for compressing audio which does not always use the same number of bits to record the same duration of sound A Windows interface between applications such as Audacity and the soundcard driver. DirectSound was released in as a replacement for the older MME and has an option to bypass the kernel mixer and so reduce latency The most recent Windows interface between applications such as Audacity and the soundcard driver. WASAPI was first officially released in in Windows Vista Zero Crossing The point where a line joining the audio samples crosses the zero binary line A lossysize-compressed audio codec and its reference audio codec implementation. AAC files usually have M4A extensionwith variants such as M4P protected and M4R ringtones. Usually gives better quality for the same bit rate than the older MP format. These have the same AIFF extension as classic AIFF and are identical to it except for being Little-endian like WAV format. It is not an audio file format like WAV that uses thousands of samples to record the full sound of the notes actually being played A lossysize-compressed audio format mainly used by the broadcast media A lossysize-compressed audio format which is the main format for transmitting audio over the internet An Open Source lossysize-compressed audio format, strictly speaking the Vorbis format in a container having OGG extension A container format, almost always used for lossless signal, uncompressedPCM audio. Windows Media Audio is a lossysize-compressed audio format developed by Microsoft. It is a proprietary technology that forms part of the Windows Media framework. WMA consists of four distinct codecs. The original WMA codec, known simply as WMA, was conceived as a competitor to the popular MP and RealAudio codecs.
Generating a waveform with many points with Trueform Generators
Generating a waveform with many points with Trueform Generators
Many factors must be looked at in order to provide captive polar bears with successful enrichment devices and more research needs to be conducted in this area to determine which conclusions will garner the most support (Ames, 1993).
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For days at a time he was capable of forgetting that he had ever.
Moving from unit testing to system testing is an important component of the course.
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Many factors must be looked at in order to provide captive polar bears with successful enrichment devices and more research needs to be conducted in this area to determine which conclusions will garner the most support (Ames, 1993).