Have you noticed the fact that if a " hi-fi car", I should say a "car hi-fi", passes by, you and the drivers of neighboring cars with their windows open, are listening lower notes better than the car driver himself and you are wondering "how on earth this guy can stand this noise?"...
Well, he does not listen these deep notes. You are exposed in the open air with unlimited space (unlimited wavelength) and so you are able to listen the lowest notes produced, which is not the case with the driver (confined wavelength). Driver is listening to some low notes but these are coming from outside (cars are not regarded to be that much well isolated environments).
Just consider and evaluate the fact: Why speaker manufacturers, reduce the frequency response between 80 & 110Hz? Because in this spectrum, normal listening rooms "help" with their dimensions.
Frequency range from 20-50Hz though, due to our limited space we have available in our listening rooms, is a difficult area, and what we are trying to do, is increasing the volume of the available frequencies (subs etc.) and have the illusion that we are gaining low notes. Only big environments can give you true low notes...
The examples you have mentioned about trumpets - Jericho walls and the soprano - breaking glass, are very good, so I presume you agree that frequency is proportional and relative to MEDIUM and DIMENSION (volume, mass).
Now, back to my question, my humble opinion is that the listener will not hear (in theoretically isolated room) below 40Hz, and the diver will not hear below 154Hz. (if I can recall, sound speed in water is 1233m/sec).
My answer to your question is that the listener is going to listen to all frequencies. The issue is what frequency is going to listen more. And what we are trying to succeed with hi-fi is to be able to listen, in a certain listening spot, all frequencies with the same volume they are produced from the source.
Now to the turntable issue. Low frequencies bother the most solid materials but not only them. Jericho walls have fallen by trumpets and the sopranos break glasses not the basses.
Turntables (and every equipment) due to their dimensions and material, are more vulnerable in frequencies they resonate. So, turntables are disturbed more by mid and high frequencies rather than low ones.
Of course I would vote for the other room (long cables?, another matter ...)
As far as room treatment, what they are doing is selected reflections, diffusions, refractions etc, THE ONLY THING THEY CAN NOT DO IS INCREASING A ROOM's DIMENSION !!!
I agree that sound is not transmitted in outer space WHY? Because: V = 0.
Frequency is given by the formula: f = V / (2*L), so if V = 0 then f = 0.
But then, why you ignore the other factor of the equation and that is L (length). We can assume than in a rectangular room, L can take it's max. value which is the stereoscopic diagonal Lmax = SQRT of SUM of the 3 squares of the room's 3 dimensions. So the larger the L, the lower the frequencymin the room can produce.
Human brains get excited by the ear's membrane which vibrates from a certain FREQUENCY, produced by a certain WAVELENGTH. If this wavelength can not be produced, this particular frequency does not exist.
Let me pose the following questions:
* Q1: If we had a source that can produce every possible frequency in an isolated closed environment with atmospheric air and a max. dimension of 4 m., what would be the lowest frequency a listener inside the room could hear.
* Q2: The same question if the room was full of water, what would be the lowest frequency a diver could listen.
It is always better if you remove any source of sound pollution from the turntable. The ideal is to put it in another room.
As far as frequency selection as you say in a small rooms, I can not imagine the possibility of designing a room able to filter out certain frequencies. If you could do that you could make a lot of money!
What is the mechanism creating a sound if the appropriate wavelength can not be formed in a confined environment!!! I would like you to show me some literature on that.
Here are 2 questions I would like you to think off:
* Q1: If a woofer is very close to a turntable, is it going to perform the same, better or worse than having it away from it?
* Q2: The same question with a midrange close to the turntable.
All frequencies are heard in all environments except in the outer space where no air exists.
You did not demonstrate to me the mechanism.
Are you telling me that big waves can be formed in a small lake, IS THAT SO?.
I see you admit with your research you mentioned that the cars had their window open (that means that now you have not a confined environment) in order for the driver to hear the low frequencies BUT NOT WITH CLOSED WINDOW, THEN YOU DO NOT HEAR BUT YOU FEEL THE PRESSURE.
Could you please explain to me:
* Why ORGANS can not be placed in small environments, but you always see them in Churches.
* Why low notes are better realized in CONCERT HALLS than in our houses.
* Why, big speakers are feeling better placed in big listening rooms and small speakers are working better in small rooms.
* Why making a hole in a shelve is better (break the resonance they say...).
* etc., etc.
SOUND IS ALWAYS RELATED TO THE ENVIRONMENT...
You do not need the full length of a wave to hear the sound in a confined environment. In acoustics this is called "forced excitation".
Apart from the sense of hearing, we feel the waves through Bone Induction.
We call acoustic frequency the frequency spectrum we realize only through our sense of hearing.
1 - 20 Ηz are frequencies which are not heard by human ear.
It has been established through research performed in England that many of the road accidents are caused by low frequencies within the car (with the car window slightly open 2-3 cm) resulting in driver's lost control of the car.
Ref. The effect of low frequencies in road accidents (Journal of Sound and Vibration)
How can you hear 20Hz, if sound cannot form the required wavelength?.
Explain to me with what mechanism because I insist, according to Wave Theory this can not happen.
I can not understand the phrase "feel with all my senses" (if you mean woofer's vibration which moves the car, I agree, you may feel even 1Hz, frequency of the car suspension, but that is not sound!)
The following formula is applied: f=344(m/sec)/[2*length(m.)].
The answer to that, in a few words is yes, you can "HEAR" 20Hz in the car. This can happen even in a telephone Box.
I have put the inverted commas because I use the word HEAR in it's broader sense, the sense of feeling or, IOW, I receive waves with all my senses I have available.
My answer is based on my scientific knowledge and my studies.
Chris Kantarelis
Κυρ Ιουλ 05, 2009 7:40 am
