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Numerous hardware and software products are now available that provide auditory and visual interactive feedback for speech-language therapy applications.  Often, however, they are limited in application to a single user.  Thus, many useful software applications are best suited for individual therapy or self-drill instruction.  Service delivery however, often involves small group or classroom instruction.  Technology that can provide stimulating multisensory presentations that are instructional and  motivational to groups of clients is now available and is the topic of this article.

The Multisensory Sound Lab developed by Oval Window Audio has proven to be particularly useful for group, as well as individual intervention.  Originally developed for use by deaf children, the system is currently being used to provide information about sound for classes of normally hearing students as well as deaf and hard of hearing students of all ages in many educational and therapeutic settings.  The Sound Lab is currently being field tested at the University of Oklahoma Health Sciences Center, Department of Communication Sciences and Disorders.  Our discussion will begin with a brief overview of the Sound Lab technology and continue with example applications for the speech-language pathologist.

The Technology
The Multisensory Sound Lab is an audio system that not only amplifies sound through loudspeakers, but also simultaneously transforms sound into floor vibrations that can be felt through the body and seen by way of colorful visual displays.  The Sound Lab electronically processes sound signals from microphones, musical instruments, recordings and other sources, and directs them to loudspeakers and a special vibrating floor. People sitting or standing on the floor perceive sound as vibrations.  High pitch sounds that are outside the 20Hz-500 Hz range are electronically transposed downward to enhance the vibrotactile experience.  In addition to pitch information, feedback concerning intensity and rhythm is perceived through the vibrating floor.

A 1/3 octave spectrum analyzer called the Visualizer displays the harmonic content of sound on a color TV as vertical bars changing in location and height depending upon the characteristics of the signal.  The LumaSound Light is a seven foot tall column made of translucent plastic containing three banks of color lights that respond to different frequency bands and intensities of sound.

Accessory equipment that is being used with the Sound Lab include a laser that displays the rhythmic patterns of sound as constantly changing abstract shapes projected on a wall or screen, an oscilloscope for displaying sound wave forms, a tone generator, electronic stethoscope, drum machine, tuning forks, electric guitars, games and induction loop assistive listening systems for hearing impaired Sound Lab users.

Application 1:  Purposeful Vocalization Activities
Purposeful vocalization is a primary goal of early speech intervention for severely expressively delayed, multi-handicapped, autistic, or hearing impaired children is purposeful vocalization.  The Multisensory Sound Lab is especially useful in maintaining the attention of these children and to reinforce gross vocalization.  Children may sit or lie on the vibrating floor.  By electronically transposing the child's voice down one or two octaves, the child will be able to tactually sense their voiced productions through the floor.   With frequency transposition, some hearing impaired children may also be able to hear their own voices for the first time. When ambient room lights are dimmed, the LumaSound Light provides attention grabbing, colorful and immediate feedback for any of the child's vocalizations.  The phonatory intensity level required to trigger feedback can be adjusted with the microphone input gain.  The magnitude of floor vibration and light sensitivity can be adjusted continuously from minimal to maximal levels.  Over time the clinician can gradually diminish the amount of visual and vibrotactile feedback/reinforcement required to assure consistent purposeful phonation.

Application 2:  Articulation Activities
The production of phonemes /s/ and /  / are frequently in error both for normally hearing and hearing impaired clients.  Across a wide variety of treatment approaches, maximally informative feedback helps to facilitate correct production.    For children, the seven foot tall LumaSound Light can be adjusted so that  the frequency information of /s/ and /  / (produced in isolation and syllables) trigger different color lights.  For adolescent and adult clients, visual spectral feedback from the Visualizer's television monitor can be used to differentiate the frequency components of the two phonemes.  Spectral peaks from a previous production may be stored on the screen.  Two microphones provide input to the system.  Microphones may be used both for  the clinician model and the client(s).  By utilizing the Sound Lab's pitch transposer. the audio input can be shifted down two octaves enabling the /  / production to be sensed through the vibrating floor.  Correct /s/ production does not result in floor vibration that can be felt.  An attached cassette deck allows recording and playback of articulation targets.   The Sound Lab's visual and tactile feedback is also useful to reinforce stop Vs continuant phoneme contrasts.

Application 3:  Group or Individual Voice Activities for Children
An important component in reducing or preventing vocally abusive behavior is for children to understand the difference between damaging vocal behaviors, and acceptable or hygienic vocal behaviors.  Because laryngeal function and voice acoustics are conceptually abstract and not directly visible, the clinician may rely heavily on diagrams, role plays, and abstract metaphors to achieve optimal phonatory behaviors and acoustic productions.  A strength of the Multisensory Sound Lab is that sound (voice) and the physical production of sound can be made more concrete, tactile and visible in ways that are both fun and motivational.  For example, children can input loud and soft sounds from  toys, their own voices and other sources.  They can imitate large vocal fold excursions with loud hand clapping.  Children quickly gain a clear understanding of how loud hand clapping can sting the hands and loud phonation can injure the vocal folds.  This concept can be generalized easily to hearing conservation activities that show why loud sounds can injure the ear.

Self-monitoring of vocal loudness can be a difficult challenge for children and may not generalize readily to group activities outside of the therapy session or classroom.  When provided with visual and vibrotactile feedback, even young children can quickly identify when sounds are "too loud" or "just right".  Over time, the clinician may reduce the variety and magnitude of feedback so that children can attend to auditory information alone when judging vocal loudness. 

Summary 
The Sound Lab is useful for both group and individual activities.  Clinical intervention that targets sound discrimination and identification, or production of speech targets differing in gross duration or frequency information are well-suited for the multisensory format.  Components of the system provide immediate and motivating feedback to both children and adults.  Also, a concrete understanding of speech acoustics and healthy voice production can be achieved through the visual and tactile sensations of sound.

Once installed, the Sound Lab is durable and easy to use.  An informal survey of our student clinicians and clinical faculty members revealed that 45 minutes were needed to become proficient in operating the equipment and accessory devices.  In 12 months of use,  we have not experienced any equipment failures.  Our major complaint with the system has been the inability of the Visualizer to resolve and display acoustic information below 300 Hz.  Considering the very low cost of this component ($300), this limitation is not serious.  Fine discrimination and production activities may be addressed using other visual feedback systems.

Assembly of the vibrating floor is not difficult, but the floor is not easily moved once installed.  A semi-permanent space should be allocated for the Sound Lab.  The modular 4' x 4' interlocking floor panels allow for a great deal of flexibility in setting up the system in classrooms and therapy areas.  With our 12' x 12' floor made up of nine panels, 15 children or 9 adults can be seated comfortable on the floor.  In our clinic we do not provide clinical treatment or prevention education for groups larger than 15.  Thus, the sound lab floor dimension has not been a limiting factor.  Small, easily cleaned cloth chairs that sit directly on the floor are used to stabilize active children.

Our experience with the Multisensory Sound Lab has been positive. We frequently receive requests from other universities, audiologists, speech pathologists and public schools who wish to use the Sound Lab for a variety of activities.  Activities have included teaching the science of sound, speech therapy, vocal hygiene, hearing conservation, music therapy and special educational topics related to deafness.  Even the easily bored, therapy-weary client is enlivened by activities in the  Sound Lab.   With the MultiSensory Sound Lab, the creative clinician and classroom teacher will develop a wide range of activities that motivate a variety of clients.

The research and development of the Multisensory Sound Lab resulted from a Small Business Innovation Research contract with the U.S. Department of Education.  Kimberly Fisher is an assistant professor in the Department of Communication Disorders, University of Oklahoma, Oklahoma City.

For more information on the Multisensory Sound Lab, click here. Please email the authors at info@ovalwindowaudio.com for detailed references on information cited in this article. Paula Hendricks, M.A., is Educational Director and Norman Lederman, M.S., is Director of Research & Development at Oval Window Audio, 33 Wildflower Court, Nederland, CO  80466,  phone/fax/TDD: 303-447-3607.