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Room Acoustics Listening part1



The acoustic treatment to optimize the sound is different according to the type of place (form, dimensions etc.) and of the desired application (room of listening, a room of recording etc.), they are however thereof the acoustic concepts of the base that are universally applicable in a room "acoustically treated". The Technical Engineering Office of the Ing.Angelo Teobaldelli is able to plan custom the acoustic treatment to adopt in the base to the demands and where mainly, in the case of the rooms of listening, we find us to face: Control of the Resonances of the place: Sound Traps for the Low frequencies, Effect Comb, Multiple echoes, Control of the Reflections, Time of Reverberation






1. Control of the Resonances of the room: Sound Traps for Low Frequencies

The sound transmits him in the air through so that. Whence that they reflect among a pair of surfaces they can create whenever every stationary resonances of a wave when the distance between the surfaces is also a multiple of 1/2 of the wavelength. At the frequencies of resonance (tones), the sound is stronger and ten very more slowly that to the not-resonant frequencies, provoking with clarity uneven tonal quality and interference. The resonant frequencies mainly happen to the lower part, because of the relationship between the lengths of wave of sounds of low-frequency and the dimensions typical of the rooms of listening.

This wave becomes a static wave because its length is equal to the distance among the two surfaces. Every room has its frequencies of resonance. Built rooms using optimal dimensional relationships they also have potentially more distributions of these resonant frequencies. A room built with walls endowed with many angles, edges and/or ceilings has some opportunities of resonance more complicated than that characteristic of the typical rectangular rooms and the resonances, they can potentially be less severe. But, however, if we find us to have a particular dimension and/or it forms some place, the frequencies of resonance can be checked through the use of sound traps

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The Low frequencies occupy all the notes on the left half of the keyboard (Everything under to C medium). Since this is a great portion of the musical spectrum, and because every room potentially has problems of resonance in such range of low frequency is mandatory that the low frequencies are the first problem to face for improving a room of listening. The geometry of every specific room, the layout, and the in-demand application clearly, dictates the best performance to the low frequencies. I am however there, of the general improvements that can be done carefully planning the Sound Traps and the optimal positioning of the same ones to offer some sensitive improvements to the room.

2. Effect Comb (Comb Filtering)

Sound and music are propagated through so that and, therefore, they have to respect the laws of the physics of the wave. This means that when 2 so that "they collide", they doesn't bounce each other as in the case of the physical objects. Instead, in that position in the space and in that instant, they add their ampleness combining all of a sudden her thin or annulling all of a sudden their ampleness until.

Whence exactly in phase they are combined up to form an only wave of double ampleness.

Whence exactly out phase they are combined up to form a wave of void ampleness.

Whence out phase of some degree they are combined up to slightly from an only wave with a superior ampleness to the single ampleness individually possessed by each of them. The wavelength of the 2 sound waves and the difference in the distances that they have crossed it determines if theirs are added or they escape and therefore also the combined resultant ampleness. This means that there is a series of additions and cancellations of wave to the various frequencies of the sound for every determined room.



There are many potentials stung of reflection that they can cause the return of an originated sound from a source toward this last and to interfere with himself. There are also many potential ways to travel for the sounds from a source to the other causing interference. I am likewise there, many ways also for the sounds originated from the single rising multiple and/or to arrive at a position of I listen central to different instants and so to interfere each other. All these undulated interferences cause a resultant ampleness of the sound for every of them that it increases or it decreases in some value depending on the frequency (the tone) of the wave. The resultant adjustment of the ampleness to every frequency, effect comb has been called.

The comb effects are reduced putting some acoustical lining on the points of reflection responsible of the interference of the sound waves. The sound absorbing materials have to adequately be however of thickness and projected dimensions to be functional with the frequencies of every specific problem. Fixing the position of the speakers the locations of the reflections will simply move him and it will change the problem of the frequencies but the same problem won't remove him.

Points of reflection primary murals

Points of perpendicular reflection


The Technical Engineering Office of the Ing.Angelo Teobaldelli is in the degree to plan to how is the acoustical lining to use as also the sound traps to check the effect due comb to the reflections of the wave. even if the precise location of the positions of the reflections represents a complex assignment, there are some locations where the control of the waves surely reflected offers an improvement to the sound.

3. Multiple echo

There are the certain runs for the sound that they produce an echo that repeats him. Every time that the front of wave passes the listener he feels as the sound it is understood, but with a torsion. And as when he clicks with a fork on a comb in rapids succession, the sound that quickly repeats him because of the front of wave that passes the listener in continuation (the multiple echoes is a repetitive echo caused by two parallel surfaces) it produces a tone of "zinging" badge. This is known as multiple echoes and it is due to the desire of our brain to interpret the fluctuations of the pressure of air and the frequency as a particular tone. This is precisely what happens when the front of wave continually passes and quickly its ear.

The runs of the multiple echoes are located more commonly long lines among surfaces in parallel.The loudspeakers positioned among the parallel surfaces of the place they constantly send foreheads of a sound wave in the repetitive loops of these characteristic runs of the repetitive echo.


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