Mastergrade Engleman Spruce - preferably with the longest drying time and lowest moisture content.
The very best bits come from old piano soundboards where they have had all the frequencies put through them; this makes the wood more resonant at those same frequencies on a guitar.
If you wanted a lower-budget but high quality soundboard then AAA grade cedar can be cheap. It is not worth using excellent wood unless every other aspect of the guitar is of high quality and if it is balanced (for resonance and preference) as whole. I.e. don't use plastic, make tight joints and use a tight grain piece of neck wood that is in-between the pitch (finger-tap and listen) of the fingerboard wood and the soundboard. As for the sides and back; quilted figured wood generally passes vibration easily, the nicer it looks the better.. :)
air is a good transmitter of sound energy. also metals are very good due to there metallic bonding properties. most materials are best at transmitting different frequencies, aka their resonant frequency.
Antennas are tuned (resonance) to the radio signals they are receiving; glasses can be shattered by sound resonant to the glasses structure; bridges can collaspse due to resonant marching; radiation can be absorbed in treatment resonant to the cells structure.
That is the resonant frequency.
Usually very dense. sound cancelling material in the walls or coating the inside of the wall of the "soundproof" room. Also see Acoustic Foam.
There is no material sound can go through the quickest. Sound always have the same speed.
the material that was used.
A loud, deep resonant sound
Lots of mass (very low resonant frequency) Low stiffness (very high co-incident frequency) All materials have both a resonant and co-incident frequency, at which sound is transmitted more efficiently. Materials where these frequencies occur outside of the range of hearing (20 - 20,000 Hz) are better for sound proofing. With lead, the resonant frequency is below 20Hz and the co-incident frequency is about 20,000Hz.
The strings on the harp vibrate, that vibration resonates in the sound board. The thichnes and the length of the string, as well as the material and construction of the string determine frequency. Thicker and longer strings make for a lower pitch sound. Shorter and thinner strings have height pitch. The sound board amplifies the sound, and also gives the tone a character.
air is a good transmitter of sound energy. also metals are very good due to there metallic bonding properties. most materials are best at transmitting different frequencies, aka their resonant frequency.
A Trumpeter Swan is named as such because of the distinctive trumpet-like call it makes, which can be heard over long distances. The sound is loud, clear, and resonant, similar to the sound of a trumpet being played.
Antennas are tuned (resonance) to the radio signals they are receiving; glasses can be shattered by sound resonant to the glasses structure; bridges can collaspse due to resonant marching; radiation can be absorbed in treatment resonant to the cells structure.
A subwoofer case constructed from oak will offer superior sound qualities, but is slightly more expensive. Oak is a very resonant material and will properly and efficiently focus sound pressure.
Oscillations set up in small resonant void spaces in / near your mouth, set up by the movement of air. Or you have swallowed a mosquito or small bird.
It may be consonance. sound may be dull or resonant.
That is the resonant frequency.
The bathroom tiles make your voice sound more resonant.