Tutorial
< Slow Vibration, Low Frequency, Low Pitch Sound >
< Fast Vibration, High Frequency, High Pitch Sound >
People hear sound by sensing vibrations in the air with their eardrums. The pitch of the sound is determined solely by the speed of the vibrations.
a lower frequency (slower vibration) produces a lower pitch, and a higher frequency (faster vibration) produces a higher pitch.
The popular picture above gives a good idea of the frequency range in which each instrument sounds.
The human audible frequency range is between 20 Hz and 20 kHz (20000 Hz), and we can divide this range into bass, mid-range and treble.
Individuals may have different opinions on how to divide the frequency range to distinguish the sound, but here's a rough guide.
- 20Hz ~ 80Hz : Sub-bass
- 80Hz ~ 200Hz : Mid-bass
- 200Hz ~ 800Hz : Lower-Midrange
- 800Hz ~ 1.5kHz : Centre-Midrange
- 1.5kHz ~ 5kHz : Upper-Midrange
- 5kHz ~ 10kHz : Treble
- 10kHz+ : Upper-Treble
'eqTrainer' is heavily inspired by "How To Listen", a hearing skills training program from Harman International - the company that owns JBL, AKG and many other brands.
'eqTrainer' includes 'Band Identification' as one of the training features provided by 'How To Listen'.
'Band Identification' is done by alternately listening to the modulated audio and the original audio.
The user aims to derive exactly which bands have been modulated and how.
'eqTrainer' includes playlist functionality, with an audio editor.
Press the + button at the bottom right of the playlist screen to select a music file.
The audio natively supported by 'eqTrainer' is mp3, wav, and flac formats. If a file not in those formats is selected, it will be converted to flac format.
Once the song has been loaded, you will be in the 'audio editor' screen shown above.
To cut the audio clip, you can set the start and end points of the audio clip by moving the slider and pressing the 'Set Start Now' or 'Set End Now' button.
The start and end points of the 'audio clip' you cut will be indicated by an arrow and time. When you are done, press the 'Done' button and the 'audio clip' will be added to the playlist.
Each training session consists of alternating between 'modulated sound' and 'original sound' and determining which frequency range has changed.
To make this process easier for the user, 'eqTrainer' provides visualised frequency information via a 'frequency graph' like the one pictured above.
Before starting a training session, users can personalise the difficulty and pace of the session to their preference by adjusting the options on the 'Session Configuration' page.
The 'Starting Band' determines how many 'center frequencies' for the filter can be applied.
As the number of 'center frequencies' increases, the difficulty increases.
In addition to the increased number of choices presented to the user, the ability to notice subtle sound changes between more neighbouring frequencies is required.
'Gain' determines how much the filter modulates the sound source: the higher the 'Gain', the greater the change to the sound, and therefore the session gets easier.
The 'Q Factor' determines the bandwidth of the filter applied to the sound source: the larger the 'Q Factor', the narrower the range of frequencies the filter affects.
The 'Filter Type' determines the appearance of the filter applied to the sound source.
'Peaks' are represented by a raised graph and 'emphasise' certain frequencies of sound.
'Dips', on the other hand, are represented by a downward-sloping graph, which 'weaken' certain frequencies of sound.
You can also set it up so that both 'peak' and 'dip' filters appear, as shown in the photo.
The 'threshold' is used as a baseline for adjusting the difficulty based on the user's skill.
The 'eqTrainer' keeps a record of whether the user has correctly identified the modulated frequency range.
If the number of times reaches the 'threshold', it self-adjusts the difficulty by increasing or decreasing the number of centre frequencies used in the filter.
Once the session has started, the user can begin training by playing the active sound source from the playlist.
Try alternately pressing the 'Original' and 'Modulated' buttons to capture the subtle changes made to the sound source.
You can select the filters applied to the sound source by dragging the 'number selector' on the session screen, or by pressing the buttons placed at the edges.
The graph of the filters you have selected will then be coloured blue. Once you have made your selection, you can submit it by pressing the button with the arrow.
The user will then be informed at the top of the screen whether the graph they selected is correct or not.
The right side of the session's top bar shows the number of correct and incorrect answers you've given during the session.
You can end the session by pressing the arrow button on the left side of the top bar or by going back.