When speaking, I hear my own voice very differently from how others do and from what it really is. The sound differs in tone, pitch, volume, etc. For example, recordings of my singing or speaking in foreign languages sounded a lot worse than what I heard in my own head.
Is that a popular phenomenon? Or is that a "syndrome", and which parts of sensation and perception are unusual? Last, is it modifiable?
I think this is not a psychological syndrome but just a reflection of the physical procesces. As such it might not be on-topic for this site. Having this said, here is a quick answer.
When you hear your own while speaking, the sound source is in a different place than it is, when you hear a recording of your voice through a loudspeaker. In addition, when you hear your own voice while speaking, you not only hear the sound that is "in the air", but you also have the vibrations from within your body, which is an additional sound source. Others don"t have the additional source. So these two factors alone make for a very different sound quality.
Besides, not every recording of your voice sounds the same. Now, I am sure there are a lot of psychological processes at work, when your hear a recording of your own voice. Unfortunately I don't know about these. But for example the position of the microphone will greatly affect the sound of the recording. Any musician who has tried to record himself will attest to that.
I wouldn't be so sure, though, that the recording sounds worse than your "real voice". That's probably just a your subjective perspective. I also found it interesting that you talk about how your voice "really is". I think that the sound of your voice that you hear while speaking and the sound of your voice that others hear when they listen to you are both instances of your voice as it really is, just from different perspectives, whereas on a recording you could actually change the sound of your voice by means of a lot of different sound effects.
Jens' answer is pretty much spot on, but misses the fact, remembered from my undergraduate lectures, that your ears actually partially 'turn off' when you speak (or chew), in what's called the stapedius reflex (wikipedia).
The most common reference I've seen for this is Møller (2000), which unfortunately is a book, but I'm sure more information could be found with a little digging.
Møller, Aage (2000). Hearing: It's Physiology and Pathophysiology (illustrated ed.). Academic Press. pp. 181–90.
There are two sound pathways by which we hear: bone conduction and air conduction. The air conduction pathway involves vibrations in the air being transmitted from the ear drum, through the bones of the middle ear, which act as a lever, to our fluid filled inner ear. The lever acts as an impedance matcher between the air and fluid filled inner ear. It effectively provides about 60 dB of gain, although there is a strong frequency dependence, and therefore is the normal conductance pathway for hearing. The bone conduction pathway involves vibrations in our skull, typically due to vibrations in the air, being transmitted directly to our fluid filled inner ear. For pressure waves in the air there is a large impedance mismatch between the air and fluid filled inner ear making this an inefficient pathway. When we speak, the vibrations in our skull are not due to vibrations in the air, but rather vibrations in the vocal tract. This means that the impedance mismatch is substantially reduced and the normal conductance pathway when we are speaking is through bone conductance.
Things are a little more complicated because our vocal tract is not a rigid system, but rather has muscles and soft tissue. This changes the filtering characteristics of the bone conduction pathway by adding more attenuation to the lower frequencies than is typically seen when measuring bone conduction with external sources. Further, our vocal system and hearing systems are linked and there are feedback mechanisms, including the stapedius reflex, that change our perception of our speech.
Speaking as a musician and one-time music teacher, this is not just true of the voice. When an instrumentalist records and plays back a performance, it can be very disconcerting. This is especially true of beginners who often imagine they sound much better than they really do.
I suspect that the action of performing somehow suppresses the ability to listen. Musicians are often exhorted by their teachers to "Listen to what you are playing!", for example:
Listen to what you are playing. 2. Many times, we play through our music and couldn't even begin to say anything about it when we have finished!
Let's Practise: Be a Better Musician By Susan Whykes
The reason could be as simple as the brain being too occupied with producing a sound to attend to it properly. Only the most accomplished musicians can 'stand aside' from their performance to simultaneously monitor it.
