Observing the filter curve of a software equalizer Since all frequencies from 5 Hz to over 20 kHz are covered, the sweeps produced in this way can be used to check the shape of the frequency response of a filter (almost all elements in a signal path can be considered filters, see ‘About Frequency Response’). If you want to know where the markers are dropped and why, read the section ‘About Markers’. Approximately two markers are dropped each second, containing the exact frequency at that point. This means that it rises with a fixed number of octaves (or 'interval'), not with a fixed number of Hz per second. (At a samplerate of 96 kHz, the tone sweeps from 5 to 48000 Hz.) You can supply a (constant) level. With this method you create an exponential frequency sweep ranging from 5 Hz to half the samplerate of your choice. Be sure to fully document the reference tone(s) of your choice. This will allow for future fade-ins of background noise, and, more importantly, this is a safe margin for any copying effects that can occur due to the layers of tape being wound on top of each other.
If you put one or more reference tones before a recording, make a 20 second silence between the tone and the program material. These values are standard frequencies for adjusting equalization, bias, levels, tape speed and azimuth on analogue tape recorders, but are still often used in the digital domain. Classic values for such a tone are 700 Hz, 1000 Hz, and 10000 Hz, all at -10 dB and lasting 10 seconds each. A standard application for these tones is the reference tone that is often required preceding recorded material on tape or disk. You can only see these marker when the soundfile is opened in editing software that recognizes markers. A marker is dropped at the start and the end of the resulting soundfile, listing the tone’s parameters. For the samplerate you should choose the rate of your digital program material. The tone will be invariable in both amplitude and frequency. We will now go through the three algorithms, their parameters and their applications one by one.įor this tone you need to choose a frequency, a level, a length and a samplerate. Since the starting phase of the generated sine is always 0, a fade in is not needed.
We have, for instance, been using these tones for quality checks of the sample rate conversion, word length reduction and look-ahead compression algorithms in BarbaBatch (our batch sound file conversion package). Why did Audio Ease create this app?Īudio Ease has used the signal generating algorithms within Make a Test Tone extensively in the production of signal processing algorithms. In general, test tones can help detect deficiencies in acoustical, recording, signal processing and wiring situations.
There is a variety of situations where test signals come in handy, ranging from standard reference tones preceding recordings (with Make a Test Tone you can choose to introduce the specs of the testtone with spoken word), to measurement and adjustment of room acoustics. In addition it drops markers in the sound files, indicating the exact frequency or amplitude at that spot.
It calculates flexible, highly accurate signals that are saved to either AIFF and WAV (BWF) sound files up to 192 kHz.
Make a Test Tone is a generator of sinusoidal audio test signals, and spoken phase checks for speaker configuration up to 10.2.