A common question I'm often asked is: ‘how come it's possible to hear such low frequencies, because humans aren't supposed to be able to hear below 20Hz?'
Similarly…'will I be able to hear the 10Hz tones, as the spec on my headphones/speakers says they only work in the 20-20000Hz range?'
They are both good questions, with a simple answer…
The 20Hz frequency limit regarding human hearing relates to the ‘pitch frequency', which is what the tone/beat ‘sounds like'. This is also what the frequency spec for headphones and speakers is referring to. The lower the note or pitch frequency, the deeper the tones sound. The higher the note/frequency, the more ‘high pitched' the tones sound.
With most of my isochronic tones tracks the ‘pitch frequency' is usually in the 180-200Hz region. Sometimes a little lower, sometimes a bit higher. But it's always well within the range of human hearing.
The Isochronic Tones ‘Beat' Frequencies
Brainwaves are stimulated not by the pitch frequency, but by the frequency of the beat. How often the beat modulates/repeats per second.
If you hear Isochronic tones where it says they have a frequency of 10Hz, this means the beats/tones are modulating/repeating 10 times a second.
- 10Hz = repeating 10 times a second
- 5Hz = repeating 5 times a second
- 7.83Hz = repeating 7.83 times a second
When you listen to the sound of fast, regular, repeating isochronic tones, this will stimulate your brainwaves, and after a while (usually around 6 minutes), the frequency of your brainwaves start to synchronize with the frequency of the beats.
If you listened to an isochronic tones session where the tone/beat repeats 10 times a second, after a while your brain will start responding to this stimulus, and then begin to synchronize its electrical cycles, to the same 10Hz rhythm of the tones/beats frequency.
The Pitch Frequency Doesn't Stimulate Your Brainwaves
The frequency of the pitch, doesn't affect the stimulation of your brainwaves. It just relates to how the isochronic tones sound. I tend to adjust the pitch frequency to the goal of the track.
If I'm creating a relaxation, meditation or sleep related session, I will look at using a lower/deeper pitch frequency, as it's hard to relax to high pitched sounds.
If I'm creating something to make you more alert, focused or increase your energy, I'll consider using a higher pitched frequency.
So although the pitch frequency doesn't directly stimulate your brainwaves, it does play a part in making the sound more pleasant and appropriate for the session in mind.
Why Don't I Quote The Pitch Frequency For Each Track?
As a general rule at the time of writing, I don't usually quote the pitch frequencies for each track up front, just the beat frequency. This is mainly because I think it will just end up confusing a lot of people. For most people, especially those new to brainwave entrainment, all this talk of frequencies can be very confusing.
The key thing you need to know is: ALL of my tracks have a pitch frequency well inside the range of normal human hearing.
If you are concerned about which pitch frequency I've used on a particular track, just shoot me a message and I'll let you know.