1. Field of the Invention
The present invention relates generally to audio devices, and more particularly, to systems, devices and methods relating to hearing aids, personal sound amplification products, devices with limited audio bandwidth, televisions, radios, cell phones, computers, laptops, tablets, personal media players, and recording devices for improving audio clarity for those with moderate, severe and/or profound hearing loss.
2. Description of Related Art
Improving audibility, speech intelligibility, and word recognition are some of the primary purposes of hearing aid devices and personal sound amplification products. Word recognition testing at various presentation levels and their corresponding performance intensity functions are a generally accepted means of quantitatively measuring such improvement. Recent advancements in precision hearing measurement and fitting using data derived from binaural balance measurements (see United States Patent Application Pending Publication Numbers: US-2010-00310101-A1; US-201100019846-A1; and US-2011-0075853-A1, the entirety of each of which are incorporated by this reference) demonstrate that progress is being made to improve aided audibility.
Complete restoration of audibility for the hearing impaired, however, is not yet equal to the 20/20 vision correction that eyeglasses can provide for individuals with impaired vision. Much of this is due to the fact that the hearing impaired individuals have permanent nerve damage for some frequencies necessary for normal speech audibility. Precision hearing measurement and precision hearing aid fitting alone cannot overcome this sort of nerve damage.
To the individual with auditory nerve damage, speech often sounds muddled. Individuals complain that speakers need to articulate more or enunciate better. For these individuals, speech simply does not sound clear. Moreover, merely turning up the aided volume does not result in improved audibility to the hearing impaired.
The need to make speech more “clear” has focused much attention on noise reduction in aided products in an effort to improve audibility. For example, directional microphones work to diminish competing off-axis sounds. Digital Signal Processors (“DSPs”) in most hearing aids today include specific noise reduction algorithms in an effort to reduce extraneous noise. Difficulties exist however in separating extraneous noise from important speech information especially when the noise is speech from competing speakers.
Some hearing aid manufactures have attempted frequency-shifting techniques to overcome frequencies where an individual has permanent nerve damage or “dead bands”. These approaches are complex to implement and consume many valuable digital signal processor instruction cycles during each sampling period.
Adding audible noise to drive an audio signal above audiometric thresholds has been proposed by others (see United States Patent Application Pending Publication Number: US-2010-0316240-A1, the entirety of which is incorporated by this reference). This approach, however, does not replace or recreate the important speech information for frequencies where the individual has “dead bands” nor does the approach move speech information contained in the individual's “dead bands” to audible frequencies.
Sharp sound is a common hearing aid consumer complaint. Some hearing aid users complain that common sounds like a door closing, keys dropping, or kitchen noise can be painful. Amplification for frequencies where the user has severe hearing loss is difficult as sound can quickly change from being barely audible to being uncomfortably loud with only a small change in actual volume. Sharp or painful sound is usually the result of too much amplification especially for frequencies where the user deals with severe hearing loss. In addition, the United States Food and Drug Administration (FDA) has warned hearing aid device consumers: “too much amplification may cause additional hearing loss.”
Hearing aid devices and personal sound amplification products change the local sound environment for their users. These devices and products are worn by some for the greater part of each day. The United States National Institute for Occupational Safety and Health (NIOSH) has established recommendations for time dependent noise exposure criteria in DHHS (NIOSH) Publication No. 98-126 (the entirety of which is herein incorporated by this reference). Other government agencies worldwide and other generally recognized standard authorities have established similar time dependent noise exposure criteria. Currently, no hearing aid devices or personal sound amplification products measure and report noise dosage to the user and enable the user to make an informed decision as to the amount of daily usage.
Another common hearing aid consumer complaint is high frequency squealing. Squealing occurs when the audio loop gain between the receiver and microphone equals or exceeds unity. In current best practices, significant high frequency amplification is often prescribed for hearing aid users. To cancel audio feedback, some hearing aids inject audio signals that are in opposite phase to detected oscillations. Still, ear molds or other physical sound barriers must be used in many cases to attenuate loop gain below unity. This leads to consumer occlusion complaints or complaints about the physical fit of the ear mold itself.
Finally, hearing aid fittings generally require accurate measurement of audiometric thresholds at specific frequencies. Fluctuating hearing loss over a period of days, weeks or months is common for juveniles and adults or individuals with Meniere's disease. Consequently, for individuals with fluctuating hearing loss, current hearing aid technologies require frequent readjustment by hearing healthcare professionals to maintain a modicum of satisfaction.
Thus, there exists a need in the art to provide a method, system and device for improving audibility, speech intelligibility and word recognition via hearing aid devices or other personal sound amplification products for those with moderate, severe and/or profound hearing loss.