lecture7

Hearing & Sound and Office Climate: 

Hearing & Sound and Office Climate IE 565 – Lecture 7 April 6th 2005

What Annoys You?: 

What Annoys You?

Acoustic Design Considerations for Offices: 

Acoustic Design Considerations for Offices Acoustics is the science and technology of sound. For a design to be acoustical it must: Transmit sound pleasantly Have a satisfactory noise level Minimize annoyance and stress Minimize speech & communication disruptions Prevent hearing loss

What Are Sound and Noise?: 

What Are Sound and Noise? Sound is what we hear – any vibration Noise is unwanted sound.

Noise: 

Noise Masking Noise – a second sound that interferes with the primary sound of interest. Background Noise – environmental sounds that are independent from the primary sound. Competing Message – second sound of as much interest as the primary sound

Critical Noise Risk Factors: 

Critical Noise Risk Factors Frequency Sound Pressure - Intensity Sound Power Time Distribution Continuous Noise Intermittent Noise Impulse Noise

Human Responses to Sound : 

Human Responses to Sound Music Background music: Such as in a shop – welcomes, reduces boredom, covers other disturbances, helps you relax. It is subdued, and the tempo intermediate. ‘Music while you work’ – varying rhythms, popular hits, meant to break up monotony and generate excitement and emotional impetus to the ‘drudgery’ of work.

Human Responses to Sound: 

Human Responses to Sound Noise – unacceptable, unwanted sound Annoys listener and cause stress Can produce adverse social behavior Is psychological and subjective Single short tones might be considered noise Depends on mental state Can create negative emotions Can delay sleep, awaken from sleep, and disturb rest and interfere with hearing wanted sounds Can interfere with sensory/perceptual capabilities and affect performance Can change hearing capabilities

Physiological Responses to Sound: 

Physiological Responses to Sound Inner ear damage Continued exposure can lead to adverse affects in the kidney and liver Gastrointestinal ulcers Change in blood glucose Thyroid activity is affected Change in blood pressure and cardiac muscle Abnormal heart rhythms Fatigue

Effect of Noise on Performance: 

Effect of Noise on Performance As noise increases, increased arousal can cause improvement in task performance but beyond a certain intensity performance degrades Sudden noise disrupts concentration and task performance Continuous periodic or aperiodic noise reduces performance on complex tasks Physiological effects may include anxiety, helplessness, poor attention

Characteristics of Dangerous Sound Environments: 

Characteristics of Dangerous Sound Environments Sound that is considerably louder than conversational level Sound that makes it difficult to communicate Experiencing ringing in ear after being in a certain environment Experiencing muffles sound sensations after leaving certain environment

Noise in the Office: 

Noise in the Office Can make it difficult to hear wanted sounds, specially communications Can create negative emotions Can interfere with an individual’s sensory and perceptual capabilities and degrade task performance Can temporarily or permanently reduce hearing loss even if pleasant such as loud music

Methods of Noise Control: 

Methods of Noise Control Planning Using the right materials Isolating/shielding sound sources Substitution Using quieter equipment Using quieter processes Using quieter materials Modification of Noise Sources Re-directing sound

Dealing With Noise: 

Dealing With Noise Filter it out Decrease the intensity (loudness) of the noise Increase the intensity of the primary sound Increase the time the primary sound is given Change the frequency of the primary sound to be different from the noise Make the primary sound more distinct (phase shifting, sending only to one ear).

Improving Speech Communication: 

Improving Speech Communication Message, sender, receiver, mode, environment Environment: Reduce generation of noise Impede transmission of noise

Our Olfactory Sense: 

Our Olfactory Sense Smells affect us – we describe smells by how they make us feel Intoxicating Pleasurable Delightful Revolting Smells can be external or internal Can be odorless and colorless (CO2, CO) They can be strong and easily detectible (S)

Our Olfactory Sense: 

Our Olfactory Sense Smells can affect well being by producing physiological and psychological reactions such as: Nausea Vomiting Headache Shallow breathing Coughing Upset sleep, stomach, appetite Irritate eyes, nose, throat Disturbance Annoyance Depression Disrupt ‘comfort’ and enjoyment of food

Physical Climate: 

Physical Climate Temperature Humidity Noise Air movement –Physical characteristics –Psychological characteristics (comfort) Different people perceive different conditions as ‘comfortable’

Physical Climate: 

Physical Climate Comfort depends on?

Assessing Physical Climate: 

Assessing Physical Climate Air temperature: thermometer Air humidity: hygrometer Air movement: anemometer

How Physical Climate Affects Us?: 

How Physical Climate Affects Us? Our body generates heat from the food we eat We exchange heat with our environment through our skin Our comfort depends on: Clothing: helps insulate skin surface Temperature Metabolism & circulation Amount of work done by body Season

Energy Exchanges With the Environment: 

Energy Exchanges With the Environment Radiation: flow of electromagnetic energy between two opposing surfaces Convection: takes place when skin is in contact with air Conductive: takes place when the skin is in contact with a solid body Evaporation: one way. We lose heat by evaporation

Controlling Temperature, Humidity, and Air: 

Controlling Temperature, Humidity, and Air Our body maintains a constant temperature of 37 °C In cold weather, we want to preserve heat to prevent hypothermia In warm weather, we want the excess heat to escape easily to avoid dehydration and heat stroke

Effects of Heat: 

Effects of Heat Cardiovascular: ability to pump blood is limited in hot climate Muscular: power output of muscles is affected by high and low temperatures Dehydration: reduces body’s capacity to endurance and affects work performance Mental performance: deteriorates with rising temperatures (for unacclimatized person)

Effects of Cold: 

Effects of Cold Cardiovascular: increased stroke volume (blood volume), increased bp Body temperature: falls in cold weather, discomfort/constriction of airways Energy cost: O2 consumption increases for work Dehydration: due to sweating (increases because of increased work) and suppressed thirst sensation Mental performance and dexterity: vigilance is reduced, central nervous system coordination suffers, loss of consciousness, dexterity reduces, tactile sensitivity is reduced, skin receptors for pressure and touch cease to function, finely controlled tasks will be affected

How to improve physical climate?: 

How to improve physical climate?

Ergonomic Design Considerations : 

Ergonomic Design Considerations Sound level between 50 – 75 dB For intense concentration sound level shouldn’t change much Some sound is desirable If too noisy: Eliminate sound at source Reduce exposure to sound

Ergonomic Design Considerations: 

Ergonomic Design Considerations Comfortable climate depends on: Right temperature, humidity, air flow Age Work done Clothing