Getting Started - Adjusting Audio System

The flatter, the better. I mean frequency response of your whole playback system, of course. If your audio path contains any tone controls, equalizers, or sound processors, which affect the spectrum of reproduced sound, in most cases, they should be switched off or set flat, unless you know for sure that they compensate for the certain flaws. If you have the loudness compensation button on your playback preamp or receiver, it should be off as well.

Setting Volume Level

The main idea for the volume is to set the comfortable level for the whole Learn/Test exercise cycle with the same audio stuff and EQ pattern, without changing the loudness during or between separate examples. Please note that our frequency perception is heavily influenced by the sound level (for more details, see studies by Fletcher and Munson on this topic). So, at this stage, it makes sense to adjust the volume to a comfortable medium loud level while you check the audio playback using pink noise and current EQ pattern. You may need to reconsider it later for different EQ patterns/settings or other audio sources.

There is a Volume Slider with the level indicator both in percents (slider value) and decibels (relative amplitude level), which can be accessed from the Transport Panel. The latter can be opened from various places, including the top-right corner of the Audio Source window and View menu of the main menu.

It would be ideal to calibrate the audio system once, and not to touch the volume levels during the whole training session since then. There is no big problem with this when exercises are packaged into a finished and mastered audio product, like a complete CD. Software lets us gain from flexibility and the possibility to create exercises with very different settings from any audio material on the fly. However, with in-app training we also run into a kind of compromise between sound quality, overall loudness and alignment of levels between exercises with different audio sources and settings.

As my priority is to achieve the best possible sound quality without clipping as a side effect of boosting frequencies, I have decided to apply to every audio source of single-band exercise the preventive peak normalization with opposite number to current absolute value of frequency gain. For dual-band EQ patterns, I have added extra-headroom from 1 up to 3dB.

So, there is an inverse relationship between equalization depth and peak normalization level (the higher the frequency gain, the quieter the source before the equalization and vice-versa). The former can be set from ±1 to ±18 dB, whereas the latter can vary from -1 to -21 dB. Both values are displayed at the status bar at the right-bottom side of the main window, which may be helpful when adjusting the volume level under different settings.

Please, also keep in mind that when listening to external audio files in the Preview mode, the tracks are played back as they are, without any preventive normalization applied. As a result, commercially mastered and other tracks with maximized levels may sound too loud compared to the same tracks in the training (Learn and Test) modes. So, it is usually worth reducing the volume approximately by the absolute value of frequency gain before you switch from the training modes back to the Preview mode. For more convenient restoring of the Volume Slider value for training, you may use the Save Volume Level and Restore Volume Level features, available from the Volume Slider right-click context menu or from the Audio menu of the main menu.

Considering all above-mentioned, I should acknowledge that I am still in search for the optimal and technically efficient solution here, which would provide the best user experience without sacrificing quality.

Quick Checking Frequency Range and Response

To check out if your playback system reproduces the wide enough frequency range for our exercises, we will need the special calibration test audio file. To generate it, simply select File | Make and Open Calibration Sine Waves File from the main menu. After having been created, the file “1kHz__10kHz__100Hz__15kHz__40Hz Sinus Tones.wav” will be added to the Playlist and selected. To load it, you can just double-click on it or press the Enter key without changing the selection (this will automatically set the relevant Audio Source mode and switch the application to the Preview mode as well; see details about working with external audio files).

The name of the file exactly reflects its content. There are five sinus tones with different frequencies, lasting 5 seconds each, and separated with 1 second of silence from each other. All the tones have the equal amplitude, which is 20% of the highest possible (approximately -14dB).

Here is the timeline table, to make it even clearer and easier to use:

You should be able to hear the first three tones (1 kHz, 10 kHz and 100 Hz) clearly. If they vary in loudness, it is not a problem unless this difference is too big. If you cannot hear one or more of these, you have a serious issue with your playback system, which must be resolved before going on. In case only the last two tones (15 kHz and 40 Hz) are barely audible or even inaudible, you can proceed, but be aware that you may have difficulties hearing/identifying the low or the high extremes of the spectrum correspondingly.

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