The standard probe tone used with adults and children (older than 6 months) for traditional audiometric measures has been (and remains) the 226 Hz tone. However, for newborns and infants the 'standard' has been the 1000 Hz tone.

We all know hearing aids make things louder. But does it matter exactly how much louder and whether it makes it louder throughout the frequency spectrum? Everyone will say yes, it does. But how often do we check that hearing aids (or cochlear implants) are doing what we hope they are doing? Is it okay to hear well through 2000 Hz and not hear high frequencies at the level of speech? How about hearing to 1000 Hz and not well above 1000 Hz? How about hearing well only through 500 Hz? If we set hearing aids using real ear technology, do we know if the child is hearing at every frequency?

Hearing Loss & Hearing Aids: Is the Child Hearing Speech?

What speech information is available where?

Different speech information is available at different frequencies. When I was a relatively young audiologist, I worked at the New York League for the Hard of Hearing. Dorothy Noto Lewis was the director. She taught us that we needed to be able to predict a child’s hearing levels by listening to the child speak. We tried to anticipate the degree of hearing loss before testing and draw the audiogram based on talking to the child and observing response to sound.

It was terrifying when I started doing this but it was a WONDERFUL learning experience. It made it very clear to me that I needed to know what a child heard and that I needed to fix what they did not hear.

Speech Sounds: Importance of Hearing Different Frequencies

Low Frequencies:

250 Hz provides voicing cues and the first formant of /n/,/m/ and /ng?. So if a child is having problems getting voicing cues we should check if they have enough information at 250 Hz. 500 Hz provides information for manner of production, first formant for most vowels, noise bursts for plosives, and information for semi-vowels and laterals /l/ and /r/.

If a child is having problems confusing manner of consonants, we should look to where the child is hearing at 500 Hz.

Mid Frequencies:

1000 Hz provides additional cues of manner, nasal consonants, back and central vowels, noise bursts of most plosives and semi-vowels. 2000 Hz provides cues for place of consonant and additional information about manner, front vowels, noise bursts of most plosives and affricates and turbulent noises of fricatives /sh/, /f/, and /th/. So if a child is having problems hearing fricatives, we need to check how they hear at 2000 Hz.

High Frequencies:

4000 Hz provides more information on consonant production, third formant for vowels, noise bursts for plosives and affricates, turbulent noise of voiced and unvoiced fricatives. 6000 Hz provides information required for perception of /s/, and 8000 Hz provides information on turbulent noise of all fricatives and affricates. Let’s remember that you need /s/ to learn prepositions, possessives, etc. It is a critical frequency to hear.

How Do We Use This Information?

For the most part, the speech acoustics courses we took were viewed as theory. Unless you were involved in research, most audiologists do not think of this information as clinically useful. In fact, it is so very very critical. Dan Ling used to say “What they hear is what they say.” Dorothy Noto Lewis would definitely have agreed with that.

We can check that a child is hearing throughout the frequency range by getting aided thresholds and we can also listen to what the child says. It is not unusual to have audiologists and teachers, etc., say that the child is not saying /s/ or some other phoneme because he has a hearing loss or an articulation problem. But maybe he is not saying it because he cannot hear it!!

Listen to the kids

If a therapist says that a child cannot hear /s/ don’t wait for the child to outgrow it. Check that the child is hearing high frequencies. If not, fix it. If it turns out he does have thresholds in the high frequencies, then we know something else is causing this, and the therapists know they need to fix it. DO NOT ASSUME. Test and find out what is real.

How to redact in adobe reader. RogerEbert.com.

I can tell you one thing for certain: if a child does not hear high frequencies, he will not be able to use that information for language learning.

Eminent Technology's Multimedia Speaker Test

This page was awarded a LookSmart Editor's Choice Symbol of Excellence

These test are provided to help you make sure that your multimediaspeakers are set up and performing correctly. Information is providedabout each tone to help you understand what it should do. We suggestthat you read these notes.

First we have to provide you with the usual warnings about damageto your multimedia speaker. A few of the test tones provided herecould be inaudible but damage your multimedia speakers IF youturn the volume control up. However for all of the test includedhere, no damage will result if you leave the volume control atits normal listening position. (Owners of the Eminent TechnologyLFT-11 do not have to worry about damage)

250 Hz Sine wave test tone - This test tone is a sine wave whichhas no harmonic content. It should sound like it comes from thecenter of the monitor if you balance control is set correctly.The frequency or pitch is close to middle 'C' on thepiano, actually a little flat, and it should sound clean. If you hear buzzing or other sounds besides a single tone make surethat your mixer and all volume controls are set correctly.

500 Hz Left Sine wave test tone - This test tone is one octavehigher or twice as high as the above test. Again it should soundclean and pure with absolutely no distortion or buzzing. It shouldonly appear to come from the LEFT speaker and nothing should comefrom the right speaker. IF the sound comes from the right speakerthen your speakers are attached incorrectly and the cables shouldbe moved at you amplifier. Move the wire from the left speakerto the opposite speaker output plug or connector on your amplifierand move the wire from the right speaker to the remaining plugon your amplifier.

500 Hz Right Sine wave test tone - As above, this test tone shouldappear to come from the Right speaker and nothing should comefrom the left speaker.

Pink Noise Monaural - Pink noise is a form of noise that theoreticallycontains all frequencies. It should sound somewhat like rain ona rooftop. Pink noise is defined as having equal energy per octaveand it is an important signal for loudspeaker testing if you havespeaker measurement equipment. In this example, if your speakersare in phase, the sound should appear to come from the middleof the monitor.

Pink Noise with Reversed Polarity - This is the same sound as above, butrecorded with its polarity reversed. Here the sound should appear to come fromthe left and right speakers individually, or beyond the outsideboundaries of the speakers. If it sounds like this noise is comingfrom the center of your monitor then your speakers are wired incorrectly. To correct this problem you will need to switch thepositive and negative wires at there terminals on ONE speakeronly and it would not matter which one you change.

30 Hz Tone - This is a very low frequency tone. The majority ofmultimedia speakers will not play this frequency. Although thisis not the lowest frequency found in music or multimedia it isa stringent test for a multimedia woofer. If you turn up the volumeon this test , you might hear distortion before you hear the testsignal. If your multimedia speaker can play this then you arein the big leagues.

50 Hz Tone - This is also a very low frequency test tone. Ifyour system will not play the 30 Hz tone above it might reproduce this tone that is a little higherin frequency. The same rules apply as above. A good multimedia system should reproduce this signal cleanly and without any distortion or buzzing. This tone is also a little easier for the human ear to detect and recognize as sound.

100 Hz Tone - This tone can serve two purposes. First if your multimedia speaker has very limited low frequency response and it failed to play the lower frequency test tones above, then try this one. Second, if you are using more than one multimedia system in a surround sound application, or a subwoofer with a multimedia system, then you want both systems to be in phase with each other. You want all of the speakers to move in the same direction at the same time. If you switch the phase of one speaker system while playing this tone, the loudness of the tone will change. When the two systems are out of phase, you will hear much less sound output at this frequency and when the two systems are in phase this tone will be loud. (Changing the phase means reversing the wires of one set of speakers,left and right, relative to the other. You can do this at the amplifier output terminals, or at the speaker input terminals by connecting the positive wire of the amplifier to the negative wire of the speaker teminal along with the negative wires at each into the remaining positive terminals. DO NOT do this with the amplifier turned on as it could be damaged.)

1000 Hz test Tone - This test frequency is also a sine wave. Fortesting purposes sine waves are used because they are difficultto reproduce accurately and any audible harmonics are a form ofdistortion in your playback system. This frequency is sometimesused as an test tone for radio stations or TV stations.

10,000 Hz test Tone - again this is a sine wave but at a veryhigh frequency. Subjectively, this is difficult to describe becauseit is a very high pitch and you will probably barely be able tohear it even if your ears are good. Most multimedia speakers willplay this tone. This is generally not perceived as a musical note.

15,000 Hz test Tone - Also a sine wave but at such a high frequencythat many adults might not be able to hear it and many multimediaspeakers might not play at a loud enough level to be audible.Our ears are naturally insensitive to frequencies this high. Wedo not recommend turning up the volume on this one. If you havea multimedia speaker with a tweeter then damage could result ifthe speaker is turned up loud for even a short period of time.

Thats it. If your multimedia speaker played all of thesetones and did so correctly then you not only have a good multimediaspeaker, but have good hearing as well.

Here are some links to pages with 3D sound effects that can be reproduced with two channel sound systems. The Eminent Technology LFT-11 excels at reproducing these sound effects because of the directional characteristics of the flat panel transducer.

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