Digital audio is commonplace in modern media, from music streaming to podcasting and film production. Digital audio has foundational elements, being sample rate, frequency, and bit rate. These technical properties determine the quality and fidelity of sound reproduction within the digital domain.
There are also many ways to modify and enhance or distress the sound within digital audio workstations. Plug-ins such as graphic equalizers allow the sound of the audio to be sculpted ie the sound may be harsh, soft, high, low sounding for instance, changed using graphic equalizers or other frequency filters.
Using graphic eq has allowed AudioMan to shape the frequencies of popular audio masking sounds for tinnitus, using files such as white or pink noise.
Sample Rates, Frequencies, and Bit Rates
At its core, digital audio converts analog sound waves into a series of numerical values. The sample rate dictates how often these measurements, or "samples," are taken per second, expressed in Hertz (Hz). For instance, a common sample rate (used for audio CD formats) of 44.1 kHz means 44,100 samples are captured each second. This standard rate is tied to the Nyquist-Shannon theorem, which states that to accurately reproduce a sound when created for digital audio, the sample rate must be at least twice the highest frequency audible to humans, which is roughly 20 kHz. Therefore, 44.1 kHz captures frequencies up to 22.05 kHz which covers the human hearing range of 20 Hz to 20 kHz.
Frequencies represent the pitch of sound, with lower frequencies (eg. 50 Hz) producing bass tones and higher ones (eg. 10 kHz) creating treble. The sample rate ensures these frequencies are preserved in digital form. Meanwhile, bit rate reflects the amount of data used per second, impacting dynamic range (the difference between the quietest and loudest sounds). Bit depth, often 16 or 24 bits per sample, determines this range. A 16-bit depth (used for commercial CD's) offers 65,536 possible amplitude levels, while 24-bit provides over 16 million, yielding finer detail. Bit rate, calculated as sample rate x bit depth x channels (eg. stereo = 2), might reach 1,411 kbps for CD-quality audio (44.1 kHz, 16-bit, stereo). Higher bit rates mean richer sound but larger file sizes.
MP3 is a common format Online for downloads and uses lossy compression to shrink audio files to about one-tenth the size of uncompressed formats like WAV or CD audio, while still retaining excellent sound quality for listeners. As storage space allows for more and larger files, it has become common to use higher bit rates for mp3's such as the ones we offer for downloading in the AudioMan tinnitus masking sounds library at 320 kbps, offering better quality but will take up more space.
Graphic Equalizers: Shaping Sound
The graphic equalizer is a powerful tool we use for manipulating audio frequencies in the studio. This digital plug-in divides the audible spectrum into bands, typically 5 to 31, each centered on a specific frequency ( 60 Hz, 1 kHz, 8 kHz etc). By boosting or cutting these bands while also determining the dynamic width of that action, the engineer can enhance or reduce bass, clarify or cut mid range sound, or tame harsh treble high pitched sound. For instance increasing the 100 Hz eq band adds warmth to a kick drum, while reducing 3 kHz might soften a piercing vocal or take out some of the sibulence.
Graphic equalizers work by applying gain (measured in decibels, dB) to each band, reshaping the frequency response. In music production, this precision tailors sound to genres or playback systems. In live settings, eq can counteract room acoustics, reducing feedback at problematic frequencies for a more refined sound.
Tinnitus and Audio Masking
Tinnitus, a persistent ringing or buzzing in the ears, affects millions, often with no cure. Its perceived sound varies from high-pitched whines near 4 kHz or low hums around 200 Hz. Audio masking offers relief by introducing external sounds to obscure the tinnitus by distracting your brain to this specific sound or frequency. People also find relief from full bandwidth white noise, covering all frequencies equally, or pink noise which is duller and lower, can blend with the ringing, reducing its prominence.
Specific frequencies tailored to the tinnitus pitch you are suffering from, say a 6 kHz tone for a matching ring can be more effective.
Notch therapy, filters out a specific tinnitus frequency while retaining others, which can retrain the brain to ignore the removed frequency, being a match for your tinnitus. Devices like hearing aids or apps deliver these sounds, providing customizable relief. Alternatively, visit our page of Notch Filter Sounds and see if they may work for you. Once you have estimated your frequency tone (you can do this on our library page) you can play samples of sounds within that range and then download the full 1hr file for offline use.
