Classroom Amplification Makes an Academic Difference James C. Blair, Ph.D. Utah State University Academic Findings Ray, Sarff, and Glassford, 1984 Amplifying a classroom helped children score higher on academic achievement tests Gertel, McCarthy, and Schoff, 2004 Amplifying a district helped children improve their academic achievement test scores by as much as one grade in one year Especially helped the Title I students and ESL students How Important is Listening? Two-thirds of a student’s day consists of listening to and participating in spoken communication Listening environments need to be free of acoustic and non-acoustic barriers Other Findings Teacher absences due to loss of voice or fatigue is reduced Student’s interest in and attention to teacher improved Behavior problems are reduced Fewer questions asked that are for clarification purposes Increased student participation in class when a pass-around microphone is used The Problem As talker moves away from the listener the signal decreases 6dB every time the distance is doubled (distance is a problem) Start at 65dB HL, 6” from mouth, at 1 foot the intensity is 59dB, at 2 feet the intensity is 53dB, at 4 feet 47dB, at 8 feet 42 dB, and at 16 feet it is 36dB Noise is a problem A normal listener at the back of the room, if it was very quiet, would have a signal-to-noise ratio of +1, if no children were in the class. With children the background noise is going to be at least 45dB, or about -3dB A second problem is reverberation Reverberation occurs when sound encounters a hard wall Sound bounces around a room The effect of reverberation is slurring of speech as you move away from the talker Normal listeners do best when reverberation times are below .6 seconds The Overall Problem When noise, distance, and reverberation are combined the result is speech is difficult to understand For normal listeners a +6dB signal-to-noise ratio leads to a 9% decrement in speech recognition When a reverberation time of .7seconds is combined with a signal-to-noise ratio of +6dB word recognition scores decrease by as much as 20% A student at the back of the room has a huge disadvantage So Why Don’t We Complain It’s always been this way We figure out strategies We get notes from the teacher/presenter We read the text or the references We talk to our friends about what was discussed We sit close to the front of the room We would never allow children to be taught in a dark room, but we will allow them to be taught in a room in which they can not hear well Study Five different classrooms used in the study. All were similar in size 30 to 35 feet deep 32 to 40 feet wide All met ANSI standard for noise and reverberation RT 60 .32 Noise Criteria 32 dB Four teachers used classroom amplification, one did not A pass-around microphone was used in one classroom regularly, but either sporadically or not at all in the other three classrooms Procedures A measuring microphone was placed on a tripod, positioned at the level of the child’s ear (placed near a child’s ear) Measurements were made at 9 different locations in each room (back center, left back, right back, left center, middle center, right center, front right, front left, front center) Measurements were made in 10 minute increments The Time, Energy, Frequency (TEF) system was used to obtain measurements Signal-to-noise ratios with infrared classroom amplification Obtained signal-to-noise ratios were on average between +13 to +20 dBA at every position measured in the rooms One classroom was not fit with a classroom system and all other teachers were asked to turn off their systems for 5 minutes during the data collection. The average signal-to-noise ratios were between +2 and +6 dBA without amplification Actual Conditions (unamplified) Teacher asked children to read in a random order around the classroom. Average sound level at the microphone based on distance away from the microphone. 2 feet - 59dB 3 feet - 56 dB 6 feet - 55 dB 12 feet - 46 dB There are times when the sound level is 13 dB less intense than at other times. Results: Unamplified Classroom Teacher’s measured vocal intensity; Front of the room at nearest student’s desk was 58 dBA, with a range of 50 to 65 dB Middle of the room at child’s desk, the level was 52 dB, again with a range of 40 to 60 dB At the most distant point, this is measured as being 18 feet from the most common place from which the teacher presents information, was 48 dB with a range of 40 to 52 dB Implications The results indicate that at the front of the room the average signal-to-noise ratio was +15 with a range between +8 and +20 In the middle of the room the S/N ratio was 8 dB with a range between +1 and +10 At the back of the room the S/N ratio was 0 dB with a range of -15 to +6 dB Implications (continued) Depending on where the child is seated at any given time changes the amount and quality of input available There are times when everything is audible and other times when information is not audible at all At best the input to children is variable The child who has any kind of hearing problem is getting at best variable auditory input (about 10% of the students) Remember this room meets ANSI standards Amplified Classrooms In these classrooms all speakers were in the ceiling, providing direct sound to most of the children. No matter where the child was seated in the room they were getting no less than a +10 signal-to-noise advantage. When the hand-held microphone was used the same advantage was present for the children as for the teacher, when not used it was like the results in an unamplified room. Results (continued) Observations: In the classroom with no amplification Many students did not listen well when the teacher was talking After the teacher explained an assignment on a poem and the children started to work, the teacher noticed one child looking around as if trying to discover what to do. When the teacher asked if she had started to look at the poem, the student said, “Oh, I thought you were talking about some kind of foam and I didn’t know what you wanted us to do.” Little differences can make for a great deal of confusion Logan City School District Few classrooms have used systems for many years Middle School was convinced that a system for their school was important Opted not to repave a parking lot and used the money to purchase audio enhancement for all instructional classrooms Legislature provided money for technology Superintendent and Board decided to use the bulk of the money to put audio enhancement in every classroom in the district Current Findings in Logan City Schools Three-hundred five teachers (K-12) were surveyed One-hundred sixty-five responded (54%) Questions and answers: Do you have classroom amplification in your room? 93.9% yes; 6.1% no Do you personally use the equipment? 89.6% yes; 10.4% no How often do you use the equipment? All day, every day: 48.2% When presenting information: 28.4% Occasionally, for special presentations: 10.6% When I think about it: 5.7% Other: 7.1% (don’t use it when there are groups in the class) Findings (continued) Do students use the microphone? Yes, 59.1% No, 40.9% How often and under what conditions? Pass the microphone around during class discussions: 3.3% Use the microphone when presenting in front of the class: 68.5% They use the microphone whenever they are talking to the whole class: 17.4% Do guests in the classroom use the system? Yes: 62.3%; No: 37.7% How often and under what conditions? When reading a story to the children: 29.5% When presenting information to children formally: 61.1% Whenever a guest talks they use the system: 61.1% Findings (continued) What is your impression of the system? I believe students are more attentive: 80.1% I can control classroom behavior more effectively: 65.2% It helps children in my class perform better: 53.9% The children like it when I use the system: 65.2% Because I don’t need to talk loud, or yell, I am less tired at the end of the day: 66.0% I don’t think that the system helps at all: 5.7% How important do you think an amplification system is in a classroom? Detrimental: 0% Not too useful: 8.6% Useful: 13.2% Quite useful: 11.8% Very useful: 35.5% Essential: 30.9% How to make it better Put it in the gym: 2 Need hand-held mic: 19 Cuts out all the time: 2 Mic too heavy: 18 Need smaller mic: 15 Needs to connect to all systems: 13 Mic Reverberates/Feedback: 6 Too soft: 2 Dead places in the room: 1 Too loud: 1 I have a loud voice, don’t need it: 2 I wear it for hard of hearing child: 2 We need complete technology classrooms: 2 How can we make it better? (continued) We need someone to maintain it and teach about it: 3 I love it: 6 It is wonderful: 3 Amazing: 1 Nothing: 2 Some Considerations Installation of classroom amplification follows no systematic procedure. In most states they are installed by the companies They are fit subjectively We are finding considerable variability across classrooms and we have had to retrofit a number Many teachers will not wear the systems Too loud I speak loudly already Does not work well Unwieldy I rarely teach the whole class at one time What to do when it does not work well I forget to put it on Microphone is too heavy and gives me a headache Unresolved issues We know that anything is better than nothing (unless it is not loud enough to make a difference) We don’t know what is truly feasible in a classroom (research says +15) Comfort Feedback Overflow We are not sure what is usual (study in process says we are at about +8) Student’s Opinions (N=258) It is easier to hear the teacher It is easier to listen when the teacher is talking “I like it when the teacher uses the system” “I feel that what I have to say is important” “I feel listened to when I can use the microphone.” Where it is used, all student respondents had only positive comments to make about the use of sound enhancement Teachers’ Opinions (4 large school districts) Students are more attentive Teachers can project their voices more easily Teachers feel less fatigued at the end of the day (no need to talk loud or yell) Teachers experience less vocal strain Teachers report that students like it when they use the system Teachers believe that students achieve at a higher level Of all the equipment in the schools audio enhancement is ranked as first or second as ”the piece of equipment that has the greatest direct influence on learning” Does it matter where the speakers are located? Choices: Speaker in the front of the room Speakers on the walls Speakers in a cluster Speakers in the ceiling Any speaker is better than none Provided they are turned up loud enough to improve the signal-to-noise ratio The best placement is in the ceiling so as to be over the head of the children. This arrangement provides the most consistent sound to every child in the room. Other arrangements provide variable intensity as the child is moved away from the speaker Classroom Amplification Makes an academic difference It reduces or eliminates the effects of noise, distance, and reverberation All students can hear the teacher and each other all the time If we are able to communicate, we are more able to learn We need to do all we can to make certain that every child has a maximum opportunity to hear Questions???
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