Learning Environments for People with Sensory Processing Disorders can be Improved by Identifying and Eliminating Auditory Triggers

Isaac Harmon, Chemistry Honors – Springman, November 22nd, 2019

Background Research:


The US Census reported in 2018 that about 1 in 59 children suffer from autism (“U.S Autism Rate up 15 Percent over Two-Year Period”). Autism is a disorder that affects how a person processes sensory information. Educational progress of children with ASD is impacted by responses to environments that have sensory triggers (Ashburner). One of the most difficult symptoms of autism can be sensory overload (Brain and Cognition). This can happen when a person’s body has trouble processing the amount of stimulation from different triggers like sound, light, textures and tastes. Sensory overload can result in discomfort, confusion, and even pain. Individuals with autism may have a negative response to environmental triggers (Landon). People with autism can also be very sensitive to sound at certain frequencies (“How Noise Affects Individuals with Autism”).


Sensory overload can affect how well a person is able to learn and negatively affect their behavior. Sound sensitivity causes significant discomfort in many people with autism (Gomes). Sensory processing problems can manifest in different ways including the inability to interact with people, language delays or deficits, the inability to stay focused on a task, etc (Ford-Lanza). A large number of people with autism actually become fearful of sounds because they are uncomfortable. A fear of sound is not uncommon in people with autism (Stiegler).


Sensory integration is important for learning and behavior. For people with autism, this function can demand a lot of effort and attention. Challenges with sensory items can negatively affect a student’s ability to take in information or remain calm. (“Supporting Sensory Needs at School”). Modifications to minimize sensory challenges, can have meaningful impact on a person’s ability to be successful in that environment. (Suarez).


Participants with autism in a study were questioned about which sensory stimuli had the biggest impact on ability to function and learn. Sound was the biggest problem, with students reporting that it provokes a physical response. Ongoing noise difficulties affected the students’ concentration, anxiety and discomfort. Since school is such a big part of a child’s life, research should be more focused on how to improve the experience in the classroom (Howe).


Sound waves are measured by how many times they go through a cycle in a second. The number of vibrations per second is frequency (Elert). They cycles per second is called hertz. Humans can sense sounds from 20-20,000 hertz. 20-80 hertz is very low, and causes discomfort in most people (“Understanding Frequencies”).  Sounds in the frequency range of 10-200 Hz have been found to cause discomfort to people with sensory sensitivities (Leventhall). Low frequency noise has a great potential to irritate someone, especially if the noise is right above the low frequency hearing threshold. Health effects for low frequency noise are worse than noise in general (Waye). Frequencies above 10,000 hz are extremely high. Many people cannot hear the sounds in above this range (“Understanding Frequencies”).


When people hear noise that they feel is unpleasant, they develop defensive reactions. The hum of a computer fan or a fridge can feel uncomfortable to someone with autism. Solutions must be found to help stop this problem (Hughes). People with sensory sensitivities report being distracted by the buzzing of fluorescent bulbs. Extreme sensitivity to sound is a common symptom of autism. 40 percent to 84 percent of people with autism experience problems with hypersensitivity to sounds (“ADHD Light Sensitivity: The Link with Hypersensitivity & Sensory Processing”).


The purpose of this project is to create a more suitable learning environment for people with sensory sensitivities by eliminating negative sounds. Many people with disabilities, like autism, have sensory processing disorders. By identifying and either reducing or eliminating things in their environment that trigger their sensory disorder, they have a better chance of success in a classroom or school.


Frequency levels in common items in classrooms are creating an uncomfortable environment for some students with hypersensitivity to sound. These students hear frequencies that are undetectable to the ears of people without sensory processing disorders. If these items are eliminated, then it will create a more comfortable and successful learning environment for many students with autism.

Independent Variable:


The independent variable of the experiment is common noise-producing items found in a classroom such as light bulbs, fans, DVD players, computers, etc.

Dependent Variable:

The dependent variable of the experiment is threshold levels of audible frequency and loudness that contribute to sensory overload in a person with autism predetermined by research.


  • Completed Surveys from 8 to 12 participants

  • Precision microphone for testing hertz and decibels


A. Gather research to understand the problem and the potential for improvement. The types of research to gather is:

1) Research explaining that people with autism or other disabilities often have sensory processing issues and what that means.

2) Research about sensory overload for people with sensory processing issues.

3) Research that explains how learning and appropriate behavior are affected when sensory overload is present.

4) Research on what items found in schools and classrooms can potentially contribute to sensory overload, particularly auditory.

5) Research about frequency levels that may contribute to sensory overload. This is interesting because people with sensory sensitivities may hear frequencies that most other people cannot hear.

B. Survey people with sensory processing issues or their parents, caregivers or health care professionals who specialize in the field to find out what things may trigger sensory overload. Look for potential things to test for in a classroom or school environment.

C. Take the data from the survey and research to determine what to test in a school. Use a precision microphone to test frequency levels of these items.

D. Analyze the data from both the surveys of people and the test results from schools to come to a conclusion about how items contributing to unnecessary auditory sensory overload in classroom environments can be reduced or eliminated. Summarize the data collected by survey regarding other potential triggers for sensory overload (possibly colors, lights and touch).

Survey Background and Results:

A survey was created and then completed by 10 participants who have or work closely with someone with autism, asbergers or ADHD.  It asked questions regarding sound sensitivity in school environments. Subjects gave answers to acknowledge the sounds they found to be uncomfortable or distracting. The purpose of the survey was to identify which sounds in schools were potentially creating a negative learning environment.
The breakdown of the 10 survey participants are as follows: 4 former students, 1 current student, 3 parents, and 2 healthcare professionals. 9 of the participants indicated they have or work with clients who have an Asperger’s diagnosis. 4 participants indicated they either have or work with clients who have sensory processing disorder. 3 participants indicated they either have or work with clients who have attention deficit hyperactivity disorder (ADHD). There were 8 female participants and 2 male participants. Age ranged from early 20s to mid 40s.

  • 6 participants said that high pitched noises cause them discomfort.

  • 1 said low pitched noise cause them discomfort.

  • 3 said both high and low pitched noise cause them discomfort.

Classroom objects that caused discomfort from sound include:

  • Hand dryers – 6

  • TV – 4

  • Lights – 4

  • Toilets – 4

  • Intercoms – 3

  • Projectors- 3

  • DVD players – 2

  • Fire alarms – 3

A common theme was sensory overload or overstimulation due to sound. This caused participants to shut down, lose focus, or avoid certain activities. Common reactions to noise discomfort were ear covering, trying to get away from the noise, crying, anxiety, anger, and pained facial expressions.

Testing Results:

In order to test the sound levels of both frequency and hertz in a school environment, a specialized precision microphone was borrowed from an engineering company in Cincinnati, Ohio and used for testing. This microphone gave very precise and sensitive readings for both hertz and decibels. The reading below is an example of how the equipment measured data.

 In this graph above, it shows that the television measured 15.73 kHz , or over 15,000 Hz. This is an extremely high reading and can cause discomfort and irritation to many people, especially if they have a sensory sensitivity. The volume of the television was muted during this test and had no effect of this reading.
The graph shows a frequency response spectrum. This is a display of the frequency components of the sound, meaning that every part of the sound that was measured is displayed graphically. Noise is not only one specific tone, is it a sum of different frequencies grouped together. As you can see on the far right of the graphic, there is an extreme peak in the reading. This means that once specific high pitched frequency is dominating the frequency response and is very noticeable. This can be very irritating to the human ear, especially to people that have sensory sensitivities to sound.
The microphone was used at Indian Rocks Christian School campus on three different occasions to get sound measurements of different items in school environments that were reported to be distracting and uncomfortable in the surveys.
The measurements are as follows:


The learning environment for people with sensory processing disorders can be improved by eliminating sounds that trigger a negative response. People with sensory processing disorders are unfavorably impacted by high and low frequency sound levels found in schools. The sensory sensitivity response from uncomfortable sounds has a negative effect on learning in classroom environments (Howe).
Over half of the people who participated in the survey reported that frequency levels of items in schools caused a disruption in learning. This number is high enough to suggest that this problem is wide-spread. Data found from testing the frequency levels in a school environment showed triggers in both the low and high frequency ranges. In the samples taken at Indian Rocks Christian School, a bathroom fan, vent hood, overhead projector and air conditioning vent tested below 200 Hz.. These are within the range to cause discomfort and pain to people with sensory sensitivities. Frequency above 10,000 hertz is extremely high. A television was tested at over 15,000 hz.
Since the majority of people with sensory processing disorders have experienced problems in learning environments due to high and low frequency sounds, and by verifying the presence of both of these, it strongly suggests that improvements can be made by eliminating them. Studies that have changed the sound impact in school environments have been done and gave positive results. With learning environments that limit sound disturbances, including sound absorbing walls, students with sensory processing disorders displayed increased sensory comfort, displayed a better mood, a more stable emotional response and better classroom performance (Kinnealey).

Applications and Recommendations:

Schools that teach students with sensory processing disorders should strongly consider adapting the learning environment so that all students can have the opportunity to learn without pain or dehabiliting distractions. Putting a student that is prone to have a negative reaction to the current environment and expecting him or her to succeed is not logical or kind. By using science to gain a more complete understanding of the sensory experience that certain students are dealing with, modifications are able to be made to improve these students’ learning.
Managing noise control has been shown to be important for students with sensory processing disorders. Using carpets and soundproof walls are helpful to students that are sensitive (Research in Developmental Disabilities). It would be very beneficial for schools to reduce the potential triggers for sensory disturbances by doing simple things such as unplugging electrical devices that are not being used to reduce high frequency output. Also, schools should use light sources that are not from fluorescent light bulbs, avoid putting air conditioners too close to classrooms with students with sensory sensitivities and schedule lawn services or other machine based maintenance to be on days where students are not in class to reduce low frequency noise.