All About Sound Field Classroom Amplification
- 1. all about sound field the listening 2 learning link
- 2. identifying the need The teacher has just asked a question If you’ve ever taken a foreign language about last night’s homework. Wanting class or tried to converse at a loud to encourage participation from those party, you know how exhausting it can who rarely raise a hand, she decides be. Trying to understand someone to call on Sally. under adverse conditions such as distance, noise, reverberation and poor “Sally, where is the acoustics — all of which are a part Rio Grande River?” of everyday life in our schools—make Sally looks at the teacher, it extremely difficult for kids to focus perplexed. Did she just on the teacher ask where the real train Good speech intelligibility is crucial for was driven? the development of auditory and lan- This scenario is typical in the average guage skills in all children. Many remain classroom. According to the Acoustical silent about the difficulty they are having Society of America, “Students with discerning speech in the classroom. Like normal hearing in the average Sally, they may become confused, or American classroom miss 25% worse— give up. Unfortunately, until the of what the teacher is saying.” teacher or a family member begins to 1
- 3. take notice of the real problem, students they are seated in the middle to back like Sally may be perceived as apathetic of the classroom. or incapable of learning the material. Fundamental to the problem is child- hood itself. Children’s auditory process- the communication es are not fully developed until their connection mid-teens, and they don’t have the life experience to be able to “fill in the Studies have proven that in noisy gaps” when they do miss information. environments the more than 2 million school children learning English as a As we’ll see in the next section, second language (ESOL) have more noise, distance, and reverberation difficulty with speech perception than all exacerbate these fundamental native English speakers, especially if problems. 2
- 4. distance Distance is a significant obstacle to speech signal, and can achieve speech understanding. Audibility 95% word recognition. decreases as the distance from the Students in the middle row, however, speaker increases (about a 6dB drop hear the teacher at 59dB — already for every doubling of distance). At a below typical classroom noise levels — certain distance, the background noise receive 66% of the speech signal, and can effectively mask the speaker’s voice. achieve 71% word recognition. A typical teacher’s voice measures 60 The situation is worse for back-row to 65dB at a distance of 1m/3ft. This students, who hear the teacher at 53dB, means that front-row students hear the receive 55% of the speech signal, and teacher at 65dB, receive 83% of achieve just 60% word recognition. 2 3
- 5. noise Noise can cause a general breakdown Playground squeals, desk and chair of communication and missed infor- movement, chatting students, fans, and mation. For ESOL students this heaters all result in a typical noise level becomes especially true as they try — of 60dB — almost as loud as busy street and often give up — discriminating traffic. And since a teacher’s comfortable between competing background speaking volume is only 60dB at 3ft/1m, noise and the teacher’s voice. she has a difficult time simply being heard by her pupils. 4
- 6. reverberation Noise and reverberation (also Vowels — the low-frequency referred to as echo) are synergis- sounds representing 60% of tic. Hard walls, high ceilings, glass speech energy, but only 5% windows, and uncarpeted floors of speech meaning — often mask reflect many sounds, often with the weaker consonant sounds, a negative impact on speech which contain far more speech understanding. meaning (compare cat, bat, sat, pat). As a person Reverberation time speaks louder, the vowels should be less than are emphasized, further 0.4 seconds to avoid obscuring meaning. decreasing intelligibil- ity, yet the typical classroom averages 0.8 seconds rever- beration time. Effects of Reverberation & Signal-to-Noise Ratio on Word Discrimination Word discrimination scores of Signal-to-Noise Ratio students with Quiet Noisy normal hearing Reverb 20 +12 +6 0 Classroom with carpet, curtains, 0.0 95% 89% 80% 60% some acoustic treatment 0.4 93% 83% 71% 48% Typical classroom (no carpet, etc.) 1.2 77% 69% 54%2 30% Figures in boldface indicate acceptable WDS scores. Without a sound field system, these scores are achievable only in quiet or acoustically treated rooms. Also note that this chart does not consider distance; even in quiet, acoustical- ly treated rooms, children at the back will have compromised understanding. 5
- 7. signal-to-noise signal-to-noise noise level of an 18-wheel truck — simplified to provide the +6dB S/N required at the back of the room. As we’ve seen, intelligibility is not the same as mere audibility (i.e., simply We could reduce the noise and rever- having the teacher speak louder is beration in the classroom by adding not the answer). In fact, intelligibility acoustic treatments and is directly related to signal-to-noise demanding that ratio (S/N) — the difference between ambient room noise and the speak- er’s voice (the signal). The greater the S/N, the greater the intelligibility. Let’s look at an example. Average classroom noise is 60dB. The average teacher speaks at 60 - 65dB measured at 3ft/1m. Thus, you would have +5dB S/N at a distance of 3ft/1m from the speaker — and we know from the pre- vious sections that this will only decline the farther away from the teacher a child sits. Indeed, typical classroom sig- the children be quiet, but this is an nal-to-noise values are -7 to +5 dB expensive or futile effort. Nor does overall (see chart for the effect signal- it address issues of distance. to-noise has on speech recognition). A more effective method is to move Yet normal-hearing children require at-risk students closer to the teacher. at least +6dB S/N — how can we This is only practical for a few stu- achieve this by altering the variables dents, however, and doesn’t allow of distance, noise, and reverberation? for much movement by either the teacher or the student. We could increase the signal by having the teacher raise her voice — Overall, these situations are not very the common solution. Yet this only encouraging. Is it worth the effort, increases teacher vocal fatigue and then, to improve signal-to-noise ratio? sick leave, and would require the Numerous studies show the answer teacher to speak at 94dB — the to be an emphatic YES. 6
- 8. the importance of acoustics There’s no getting around the impor- Finally, there’s overwhelming empiri- tance of good speech intelligibility in cal evidence showing that improved schools. Classrooms are clearly auditory- S/N results in better student atten- verbal environments — children spend tion, comprehension, test scores, and as much as 45% of the school day in on-task behavior. a listening situation. Language develop- Log on to www.phonicear.com ment occurs early in life, and what’s to order reprints of these studies more, literacy is directly related to audi- or go to the links where provided tory development. Kids who have good and download. listening experiences tend to become better readers. With the help of wireless technology, it’s actually possible to improve signal- In addition, much of the material and to-noise ratio without seating restric- vocabulary is new to students — they are, tions or costly modifications to after all, just learning. classroom construction. From an academic perspective, difficulty hearing and understanding leads to disruptive behavior. 2 7
- 9. the sound field solution It’s called sound field, and it consistently provides: • Compensation for the variables that • 8 to 10 dB S/N ratio and up to adversely affect signal-to-noise ratio 30% improved speech recognition • The ability for any child anywhere • Better test scores — in the room to hear the teacher as if often dramatically better he or she were only a few feet away • Improved attention and behavior • A focus on the teacher — • Reinforcement of language develop- not background noise or echo ment and literacy in all students 8
- 10. how does it work? In the same way that sitting close Did you catch that? Sound field uses to the teacher results in a the advantages of close proximity to positive signal-to-noise the sound source twice — first by ratio and strong speech placing the microphone close to discrimination, a wireless the teacher’s mouth where it picks up sound field system a strong signal nearly free from back- delivers a clear, intelli- ground noise, and second by placing gible speech speakers closer to the students. In signal by effect, the teacher is never more than reduc- a few feet from students, and a gentle ing key amplification brings the signal-to-noise distances. ratio above the 6dB requirement. First, the teacher wears a small wire- Amplification allows teachers to speak less transmitter with a microphone in a normal voice and since it’s wireless, placed within 6in/11cm of his or her they can move freely around the room mouth (or connected from a receiver or turn to face the chalkboard while directly to a VCR, CD player, etc. for a effortlessly maintaining the level of his surround sound kids love). or her voice. His or Her voice signal is transmit- ted across the room through radio wave or infrared light, bypassing the effects of distance, noise, and reverberation. The teacher’s voice signal is then brought close to students’ ears through speakers placed around the room. 9
- 11. does it really work? Since the 1970s over 50 studies What do audiologists and teach- have been conducted to find out just ers have to say about sound field? how much difference sound field “Students in the classrooms with an FM systems make. sound field system achieved greater liter- In Florida from 1993-95, an extensive acy gains than control students. Twice as study on “Improving Classroom many students achieved up to seven Acoustics” was conducted among 2,054 reading levels of literacy growth com- students in 94 kindergarten, first and pared to the control students.” second grade classrooms. Sound field Beata Darai, Aud, FAAA was installed in 64 classrooms, while 30 “Using Sound Field FM Systems to Improve Literacy Scores” classrooms acted as the control group. Advance for Speech-Language Some of the findings include: Pathologists and Audiologists • 96% of teacher agreed that attentiveness, listening, and “Numerous investigations have shown comprehension improved that when sound field amplification systems are used, psychoeducational • 100% of school administrators agreed and psycho-social improvements that teachers enjoyed the systems occur, academic gains were obtained • 92% of administrators thought that at a faster rate, to a higher level, and sound field enhanced class instruction with reduced cost.” and management Carl Crandell and Joseph Smaldino “Room Acoustics for Listeners Other studies have found: with Normal Hearing and Hearing Impairment” Audiology: Treatment • Vocabulary test scores improved by 12% with sound field. “Before sound field only 44-48% of • Spelling test scores of 3rd, 4th, and 1st grade pupils tested at the ‘basic’ 5th graders have been shown to level and above. After seven months of improve by 14.5%, 9%, and 22.4% sound field 74% of children tested at respectively when using amplification. the ‘basic’ and above level. Students • Comparative results from project also showed significant improvement MARRS (Mainstream Amplification in vocabulary, word-usage skills, and Resource Room Study) indicated were much more likely to answer that students in an amplified class- questions appropriately.” room showed significant improve- Linda Crozier, MA, CCC-SLP ments in Scholastic Reading W. Russell Todd Elementary School, Achievement scores. Roosevelt, Utah For many more references visit www.phonicear.com 10
- 12. which system? There are several sound field system sound quality, speech clarity, and options, each with its own special simplicity, this system lives up to its advantages and applications. name — EASYLISTENER 2. Easy to use — easy to hear the difference! A team- teaching option with a handheld mic is also available. Our popular, portable, RADIUM system let’s you choose from 16 channels on both the receiver and transmitter — no preselection of channels required. It sets up in minutes and is very afford- able, making it a great choice for first time sound field users. With two speak- ers housed in one unit, RADIUM can easily improve Unlike RADIUM and EASYLISTENER 2, the listening environment which transmit sound using radio in almost any classroom. And frequencies, VOCALIGHT uses infrared because it’s battery powered and com- light. The advantage is the ability to pletely portable, you can even use it use an unlimited number of systems for outdoor events, physical education, in the same building. Since infrared assemblies and more! RADIUM also light can’t penetrate walls, every class- features two built-in channels for room can use a VOCALIGHT. Our easy team teaching and a student infrared technology is also immune pass around mic. to interference from ballast lighting or indirect sunlight. VOCALIGHT offers two built-in channels for team teaching and a pass around mic. The new EASYLISTENER 2 transmits the teacher’s voice through four high- performance compact speakers positioned around the class- room. While this requires more installation than the RADIUM, the advantage is OptiVoice, our exclu- sive speech clarity control. Designed from transmitter to speakers for 11 Try any system for 45 days!
- 13. which features? features RADIUM EASYLISTENER 2 VOCALIGHT technology FM FM infrared frequencies 216MHz 216MHz 2.3/2.8 MHz built-in channels 2 1 2 approximate installation time 5 minutes 60 minutes 90 minutes relative cost $ • $$ $ • $$ $ • $$ number of systems per install 8 -16 19+ no limit aux input (CD, TV, computer etc.) 1 (4 with aux box) 1 (4 with aux box) 1 (4 with aux box) aux output 1 1 1 (interfacing/rebroadcasting) 3-band equalizer no yes no OptiVoice™ speech clarity control no yes no 4 wall or ceiling, 4 wall or ceiling, speakers 2 in 1 column or 1 ceiling or 1 ceiling yes – with yes – with yes – with team-teaching option additional receiver/ handheld mic handheld mic handheld mic 66x14x10 cm 21.9x5.4x16.2 cm 22x21x5 cm receiver size 25.9x5.7x3.9 in 8.6x2.1x6.4 in 8.5x8.3x1.8 in These charts are provided as an which speakers? overall guide for system selection. Recommendations may vary according to room configurations. features RADIUM 4 compact spkrs 4 distributed* ceiling cluster* portability yes no no no quick installation yes no no no cost $ • $$ $ • $$ $ • $$ $ • $$ sound dispersion very good best best good *ceilings must be at least three meters or higher than ten feet for distributed ceiling speakers; higher than 12 feet for cluster speakers. Four speakers are usually best for rooms approximately 12 30x30 ft or 9.1x9.1 m or more.
- 14. which mic? features boom earhook IR lapel FM lapel collar comfort good good excellent excellent good feedback excellent very good fair fair fair resistance sound quality excellent good fair fair fair boom mic earhook mic head-worn mics infrared lapel mic FM lapel mic (wear as shown or clip on) lapel mics infrared collar mic collar mic available in FM or infrared. FM ver- sion has mute switch collar mics 13
- 15. funding Even after they recognize the benefits If you don’t have access to a computer, of sound field, some schools and call us at 800-227-0735 then press 5, school districts don’t feel they have and ask to receive our Funding and money available — that’s where grants, Grant Writing Packet, which lists many funds, benevolent groups, and creative ways to obtain funding, the differences fund-raising can help. between funding sources, and places you can call for more information. There are numerous grants available from government education programs, corporations, and nonprofit groups totaling billions of dollars. In addition, some schools have been able to access funds through their technology budget, while others have benefited from fund raisers held by the local Parent/Teacher Association, Rotary Club, or other benevolent groups. The easiest way to begin is to visit www.phonicear.com and go to our funding guide where Phonic Ear also offers a free 45- we have links to many grant and day evaluation so that you can expe- fund-raising sources. rience firsthand how sound field can benefit both students and teachers. 14
- 16. about Phonic Ear Since we first began working with thousands of people in over 60 nations wireless systems in schools in 1968, have come to rely upon. Phonic Ear has been helping students We are convinced that once you try in every situation, from preschool Phonic Ear products you’ll be as excited through college. as thousands of other educational pro- We are headquartered in California’s fessionals about the power of sound Sonoma wine country. Here, our 140 field to capture students’ attention employees – one-third and achieve great improvement of whom have been in comprehension. with us for at least 10 Call our customer service department years – design, build, to answer product questions or set up improve, and sup- a free 45 day trial. port the prod- ucts that USA: 800.227.0735, then press 5 Canada: 800.263.8700 Outside USA or Canada: 707.769.1110 web: www.phonicear.com ©2004 Phonic Ear Inc. Phonic Ear and the names of Phonic Ear products are trademarks or registered trademarks of Phonic Ear Inc. in the U.S. and other countries 828-6880-113/Rev. A/4445 507