Hearing Loss and Hearing Enhancement

Listening and AnalysisDay 2 Lecture

Protect Your Ears!

• They are going to be the most important tool of your profession

• At live shows: Wear ear-plugs• There are a variety of effective ear plugs that

muffle sound to a lesser extent• In-ear monitors for live musicians• Reasonable levels for iPods and on speakers

How loud are sounds?

• 20dB: Ticking Watch• 60dB: Normal Conversation• 85dB: Start of risk of damage (long periods)• 90-95dB: Lawn Mower• 110-120dB: Concerts or Loud Stereos• 140dB: Jet Engine Takeoff• 160dB: Temporary Gunshot

HRTF

• Stands for Head-Related transfer function• It means: Our ears measure decibels

differently than a machine• Be even more careful: we may be hearing

18dB more than we think we are!

Noise Exposure

• We get a “Dosage” of different noises• A 3dB change will double or halve our dosage

time.• Example: A continuous sound at 89dB for 2

hours is as damaging as a sound at 86dB for 4 hours.

• 85dB is considered the starting point for hearing loss in the U.S. and Canada.

Otoacoustic Emmissions

• Our ears actually emit sound!• It is very quiet, but can be read by machinery• This is actually used to diagnose inner-ear

health• A good amount of Otoacoustic Emmissions

means that you are probably hearing well

Tinnitus

• You don’t want this!• Can be natural, but also can be a result of

hearing damage• No single known cause, but it is believed to be

a neurological reaction related to ear damage• Also can be related to “Hyperacusis” or ultra-

sensitivity to various sounds• The best known remedy is psychological

therapy

Tinnitus continued…

• 70% of people have experienced it• Think of how your ears feel after a concert,

and you get the idea• It has been linked to depression• Be aware of your environment and take care

of your ears to avoid hearing loss or Tinnitus

Live Sound Levels

• Finding ways to have a full impact without all of the noise

• A lot of what we are hearing at concerts is reflections, not just the speakers

• Fill the room, but try to minimize reflections: Raise the loudspeakers above ear level, use sound absorbtion

Hearing Enhancement

After hearing loss

• It can happen from sound exposure, and also naturally with age

• Approx. 14% of population have some kind of hearing loss, according to the article

• AHS: Assisted Hearing System, like a hearing aid

Problems with PA Systems

• The article says this is where people have the most trouble with hearing detail of speech

• The microphone may not be ideally placed to capture diction

• Sound processing, speakers and room reverberation can diminish sound clarity

• The hearing device may enhance sounds, but it may not be the BEST sounds, and may also include NOISE and REVERBERATION

Enhancing Speech

• There has been research done to enhance speech in the presence of other noise

• Think of in movies, for example, or a crowded room

• Both FREQUENCY RESPONSE, and MASKING can be an issue to make speech less intelligible

Problems with Televisions

• Speech recognition is difficult because of:• Poor sound reproduction• Low wattage speakers• Often facing the rear of the room• No separate center channel

• Stereo speakers or 5.1 surround can remedy this

Measuring Loudness Difference scientifically

Last Note

• Improving noise reduction and speech enhancement is not just for hearing impaired

• This can benefit everyone• We can here BETTER and more CLEARLY