Tag Archives | the speaker exchange

Do People Hear At Different Frequencies?

One Hertz (Hz) is one vibration per second. Higher Hertz values equate to higher pitched sounds.

Most people hear between 20 to 20,000 Hertz, but different people can have different hearing ranges. Some people can hear at 22,000 Hz and higher. Genetic inheritance can affect hearing ability just like it affects so many other traits, but there can be losses to the ability to hear the full audio spectrum, and specifically high frequencies, as we age or if damage caused by exposure to loud noises occurs. It can be normal for a middle aged man to only hear as high as 13,000 Hz. Hearing tends to deteriorate more slowly in women which is why woman often hear higher pitches more than same-aged males.

How does this affect your Speakers” If you are not hearing the tweeter in your home stereo or the high frequency compression driver in your PA, it might be damaged, or it might be that your hearing has changed.

We can help! Let us test your speakers. Bring or send us the tweeter or the whole cabinet. We can test the tweeter or driver so you can know if IT or you have the problem. We repair and replace tweeters and drivers as well as crossovers.

Factoid: Many animals communicate at frequencies outside of our audible range. Elephants use lower frequencies (infrasound) and rats use higher frequencies (ultrasound).

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Beam sound

Sinusoidal waves of various frequencies; the b...

Image via Wikipedia

A transducer can be made to project a narrow beam of ultrasound that is powerful enough, (100 to 110 dBSPL) to change the speed of sound in the air that it passes through. The ultrasound is modulated– it consists of an audible signal mixed with an ultrasonic frequency. The air within the beam behaves in a nonlinear way and demodulates the ultrasound, resulting in sound that is audible only along the path of the beam, or that appears to radiate from any surface that the beam strikes. The practical effect of this technology is that a beam of sound can be projected over a long distance to be heard only in a small, well-defined area. A listener outside the beam hears nothing. This effect cannot be achieved with conventional loudspeakers, because sound at audible frequencies cannot be focused into such a narrow beam.

There are some criticisms of this approach. Anyone or anything that disrupts the path of the beam will disturb the dispersion of the signal, and there are limitations, both to the frequency response and to the dispersion pattern of such devices.

This technology was originally developed by the US (and Russian) Navy for underwater sonar in the mid-1960s, and was briefly investigated by Japanese researchers in the early 1980s, but these efforts were abandoned due to extremely poor sound quality (high distortion) and substantial system cost. These problems went unsolved until a paper published by Dr. F. Joseph Pompei of the Massachusetts Institute of Technology in 1998 (105th AES Conv, Preprint 4853, 1998) fully described a working device that reduced audible distortion essentially to that of a traditional loudspeaker.

The technology, termed the Audio Spotlight, was first made commercially available in 2000 by Holosonics, a company founded by Dr. Pompei. There are currently two devices available on the market that use ultrasound to create an audible “beam” of sound: the Audio Spotlight and Hypersonic Sound

horn speaker is a speaker that uses a horn to get more sound (volume) from the driving loudspeaker. The horn itself does not amplify anything, but rather improves the coupling between the speaker driver (typically made of paper or, more recently, more exotic materials such as titanium) and the air (which has a very low density). Simply put, air is very light and speaker cones are relatively very heavy, so horns trick the speaker cone into believing it is very large in surface area, and very light (more like air).

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How a Speaker works detailed

The key working components of a loudspeaker are shown in the diagram below. When an electrical
current passes through a wire coil (the voice coil) in a magnetic field, it produces a force which varies with the
current applied. The cone, connected to the voice coil, moves in and out, creating waves of high and low air
pressure.

The coil and magnet assembly are the ‘motor structure’ of the loudspeaker. The movement is controlled by the loudspeaker’s suspension which comprises the cone surround and the ‘spider’. The surround and spider allow
the coil to move freely along the axis of the magnet’s core (or ‘pole’) without touching the sides of the magnetic
gap.

Eminence technology and proprietary materials mean that age-old ‘compromises’ of durability against sensitivity,
or power handling against precision of response, are more easily solved than you might imagine.

Heatsinks: In the quest for higher power density (more power and hence more sound from less space),
Eminence has progressively introduced heatsink components to selected transducers e.g. cast frame neodymium products and Kilomax. The heatsinks pass through the pole of the transducer or are incorporated into the chassis
of the loudspeaker to transfer heat away from the coil. The air currents caused by the cone movement cool the heatsink.

(from Eminence Speaker)

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Fraser Speaker Recone

Vintage Speaker Repairs our our Specialty.

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