Frequency in an objective quantity. Measured in Hz. 1 Hz is by definition one cycle of vibration per second.
Pitch is a subjective quantity. What out brain perceives as "height" of sound. It is measured in mels possibly from the word melody.
While frequency and pitch are obviously related they are not the same.
Pitch for example depends not only on frequency but also on intensity.
In general the louder a sound the more flat its is perceived ie pitch decreases.
The consequence of this appears to be very important to singing. Obviously hearing flat due to larger intensity will make us sing flat and out of tune.
Possibly relevant examples of how important this is:
The Bee Gees asking at the staying alive sessions that the 3 sing together around a mic and a little speaker close to them.
Phil Ramone also describes in his book the first thing he suspected when a singer was out of tune were the levels being inapropiate in the headphone mix.
And we have more than 50 years ago S.S. Stevens the man who established the Psycho-physics laboratories at Harvard to be fascinated by these phycho acoustics phenomena and describing them in his marvelous books.
Having a small speaker close to us when we record or a live orchestra as when Dionne Warwick singing (This Girl's in Love with You - Bucharach, Davis), her soft voice means that the acoustic levels must be low. So the singer can hear "true" pitch and nail it as it happened.
A very easy way to verify all this is to sing along while this song is being played on YouTube by holding an iPad with its little speakers on our hands. It is surprising how in tune we can sing and the less the volume of the speaker the better. In tune means our brain correctly perceives the number of vibrations per second and appropriately adjusts the vocals chords. Hence there are no beats by adding two signals with different almost close frequencies.
So why not doing this while recording on a mobile device such as iPad by just holding it close to us while it plays softly. (So no headphones or headphones at very low level?). There is a mistake in this post. When connecting a mic through the headphone socket of the iPad its internal speaker is disabled. A way around this may be to connect an external small speaker connects to the mic headphone cable. Or holding the headphones away from the ears. Or playing the headphones at the correct low volume when recording vocals.
The microphone can be very close to the singer's mouth so that it captures a very strong and clean vocal.
Omnidirectional microphones may be very suitable as they do not have a proximity effect.
If a cardioid mic is used then a Pleiades filter may be needed to compensate for the proximity effect.
A proposed setup is using the MD21 which sounds a bit bass heavy to brain perception when used for soft vocals but the responce is equalized by the iPad's low cut filter. For almost complete absence of hiss a Pleiades K117 JFET front end amplifier can be used. Pleiades schematics and concepts are open source and can be found at other Eureoelectron posts.
Setup, signal path:
Soft voice at 0-1in - Sennheiser MD21 HL at H or high Z setting - Pleiades K117 inside the mini Tuchel mic connector - iPad - (small speaker or headphones?)
This setup allows the connection of the world class Sennheiser MD21 moving coil microphone directly to iPad through a very simple one stage class A operation (electrons flowing all the time) amplification stage. As for example inside a Neumann U47 which uses just one electron tube amplifying stage with the minimum of surrounding resistors, capacitors. The Pleiades K117 contains just a K117 low noise JFET and one resistor so it can be made easily and fit inside the mini Tuchel connector. The minimum of components design preserves in the most revealing way the magical qualities of the voice. The Pleiades K117 is powered directly from the iPad's or other device's mic-headphone socket in the way electret condencer mics are. The above configuration insures unheard of low noise, naturalness and sensitivity.
A further advantage of using no headphones is increased mobility.
All needed is an MD21, the cable which contains the JFET amplifier incide the mic connector and an iPad or other mobile recording device.
The setup may even be suitable for tracking superb studio quality vocals on quite outdoor locations.
References:
http://www.soundonsound.com/techniques/classic-tracks-bee-gees-stayin-alive
Making Records - Phil Ramone - 1st edition - The Session - page 143
Sound and Hearing - S.S. Stevens, Fred Warshofsky - Life Science Library - Time Life Books - New York - Chapter 4 The Mind's Influence - page 77
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