I have a race of humanoid species, who, like elves, have better senses than humans. They live in mountains and hills. They look like humans but have longer faces, smaller eyes and are most famous for their long noses (like noses between 5-15cm). Then I wondered, if their long noses would have an effect on the sound of their voices? I know this is a far-fetched question, but could anyone help me with this one? BTW: sorry for bad english. Not native speaker. Thanks a lot!
They will definitely sound different
Most of human speech is made through changing the shape and spatial relationships between the lips, teeth, tongue, oral cavity and throat. Changes to the shape and materials of any of these structures will have an influence on the sounds that can be made. The IPA chart (pdf) shows many of the sounds that a human being can make, definitely not all sounds. You'll notice for the consonants that the ones to the left are made further forward in your throat while the ones to the right are made further back in the throat.
If your creature lacks or alters any of these vocal structures it will sound different.
For example, if the nose somehow makes the dog people's lips more rigid or so they can't be controlled at all, then they won't be able to pronounce the /p/ or /b/ sounds since those require lips to form.
The sounds of their vowels will also change since there's now a much larger resonator cavity in their skulls compared to the nasal cavity in humans. Generally, the tones would be lower because big resonators work best with low frequency sound.
A really helpful exercise would be to make lots of the consonants and vowels but pay close attention to how your mouth and throat move when you make different sounds. It will help you a lot with trying to imagine what sounds these creatures can make. Or, you can go to the Pink Trombone website (SFW, but creepy) and play around there.
Without more specific geometry it's just not possible to figure out what the exact sounds will be.
- Bigger cavities create deeper notes.
- Removing or altering vocal structure compared to a human will alter the creature's ability to make those sounds. Experiment with the IPA chart to compare what the creature looks like vs human anatomy then adapt from there.
The effect will be rather small. The sounds of human speech are formed in the oral cavity and their frequency is determined by the tension and length of the vocal chords.
Changing the nose length will not affect this system very much. In particular, they will be able to form the usual phonemes of human speech and they'll be understandable by us.
Trained singer make use of all possible resonators in their body, and the bigger noses make different resonators from the normal human noses, so one can expect some difference in the "colouring" of the sounds we make, and the difference will be biggest for singers.