Table 2 Descriptive characteristics of studies

Hearing, communication and cognition in low-frequency noise from armoured vehicles

Nakashima, Ann; Abel, Sharon; Duncan, Matthew; Smith, David

2007

n = 36;

age range:

18–55

The subjects were tested with the ears unoccluded and while wearing a David Clark headset (H10-76XL) in both passive and ANR modes (referred to as “ANR Off” and “ANR On,” respectively)

The LFN (hereafter referred to as vehicle noise) was recorded near the ear of the crew commander while standing with his upper body through the hatch of a LAV III. The vehicle was traveling on a highway at approximately 80 km/h

Attentional functioning

Four-choice serial reaction time (SRT)

For the SRT task, one of four probe letters was presented on the screen (P, G, L and S), and the subject pressed the corresponding response button as quickly and accurately as possible

1.09

(0.22,1.96)

Executive functioning

Mental addition (MA)

The MA task required the subjects to add a random sequence of eight numbers (between 1 and 16) that were presented one by one on the computer screen

-0.05

(-0.85,0.75)

Memory

Detection of repeated numbers (DRN)

In the DRN task, a series of three-digit numbers were flashed on the screen at a rate of 2/s. The subjects pressed a button when a three-digit number was repeated

0.11

(-0.69,0.91)

Higher-order functions

A logical reasoning task (LRT)

For the LRT, a pair of letters was shown at the top of the screen (A B or B A) and a statement showing the spatial arrangement of letters was shown below, e.g., “B does not follow A.” The subjects responded by indicating whether the statement was “true” or “false.”

-0.79

(-1.62,0.05)

A longitudinal, randomized experimental pilot study to investigate the effects of airborne infrasound on human mental health, cognition, and brain structure

Ascone, L; Kling, C; Wieczorek, J; Koch, C; K¨¹hn, S

2021

n = 38;

age mean: 19.76

Six sources were

assembled in total, three fully functional sources for the verum group and three dummy sources for the placebo group. The sources were designed to be installed by the setup team in the participants bedroom and then to work for several weeks autonomously and reliably. The main components were a frequency generator, producing a 6 Hz sinusoidal tone, an amplifier,a loudspeaker, and a 26 m flexible tube attached to the speake

The IS sources were configured in such a way that they would emit a steady SPL between

80 and 90 dB (6 Hz frequency) for eight hours during the participant’s self-reported habitual sleep (bed) time interval

Attentional functioning

Alertness

Concerning alertness, tonic and phasic alertness can be differentiated. Tonic arousal is a good proxy for wakefulness, where the participant is in a state of willfully maintaining his or her attention and accordingly responds quickly to an upcoming event

-0.39

(-1.05,0.27)

Executive functioning

Go-nogo

Concerning alertness, tonic and phasic alertness can be differentiated. Tonic arousal is a good proxy for wakefulness, where the participant is in a state of willfully maintaining his or her attention and accordingly responds quickly to an upcoming event

-0.57

(-1.24,0.09)

Memory

Sustained attention

Sustained attention refers to the capacity to concentrate on a routine task for a longer period of time (15 min in the case of the test)

0.01

(-0.63,0.65)

Higher-order functions

Incompatibility

Incompatibility effects occur in conflict situations, where divergent information generates a conflict in reaction tendencies

-0.52

(-1.18,0.14)

Effects of noise on mental performance with regard to subjective noise sensitivity

Belojević, G; Ohrström, E; Rylander, R

1992

n = 45;

age range:

18–32

Three different acoustic conditions were used in the experiments Background laboratory sound of 30 d B(A) Leq (measured at the subjects' seats) constituted a quiet ambient condition, while the recorded motorway noise, continuous and variable, was emitted at two levels: moderate[Leq = 55 d B(A), L 99 = 48.2 d B(A), L = 62 9 d B(A)l and high lLeq = 75 d B(A), L 99 = 68.2 d B(A), L 1 = 82 1 d B(A)]

The spectral analysis of noise showed a dominance of lower frequency components (40–400 Hz) due to the high proportion of heavy vehicles in motorway traffic

Executive functioning

The Mental Arithmetic task (MA)

The Mental Arithmetic task (MA), a test of parallel processing. A set of 15 tasks invovled mental division of two-digit numbers by 6, 7, 8, or 9, with a two-decimal result The efficiency and the depth of mental processing were estimated by the number of correct whole numbers in the results (shallow), one-decimal results (intermediate), a total results (deep), and by the time spent to complete the task

0.21

(-0.20,0.63)

Memory

The Short-Term Memory task (STM)

On a computer monitor, 25 series of seven consonants, appearing consecutively with a few seconds' pause, were shown to the subjects In addition, 12 words of different semantic categories appeared occasionally during the projection of letters Consonants had to be recalled by order of appearance and registered on a form after each series The subjects were advised to memorize the letters in groups of 3 + 4 in order to avoid the influence of individual strategies in mental performance The words had to be memorized and written only upon completion of the entire test, without attention to their order The performance was measured by the number of errors and by the number of words remembered in the groups of the same semantic category (clustered) The test lasted 25 min

-0.12

(-0.54,0.29)

Effects of road traffic noise and irrelevant speech on children's reading and mathematical performance

Ljung, R; Sörqvist, P; Hygge, S

2009

n = 187;

age range:

12–13

In the noise conditions, digital recordings of road traffic noise or irrelevant speech were played back through loudspeakers at the front of the classroom. The equivalent sound level (Leq) in the noise conditions was set to 66 dBA 2 m in front of the loudspeakers. The road traffic noise recording was made up of a background of continuous road traffic noise (~ 62 dBA) with superimposed segments of trucks passing by. The peaks in the superimposed segments were at 78 dBA

The dominant frequency range for the road traffic noise (100–300 Hz) was lower than that for the irrelevant speech (500–1500 Hz)

Executive functioning

Reading Test

The test consisted of a four-page story. With regular intervals there was a critical choice point. At these points, three words were presented. Each word was grammatically correct in the phrase in which they occurred, but two of them were wrong in the context. The task was to underline the word that was correct in the context

-0.21

(-0.20,0.63)

Higher-order functions

Basic Mathematics

This test consisted of arithmetical and geometrical problems. The arithmetical tasks were division (three problems) and multiplication (three problems). The geometrical problems were naming points in a coordinate system (two problems), understanding of the relationship between fractional expressions and areas of figures (four problems), understanding of the relationship between distance and numerical expressions (two problems), and measuring of distances (two problems)

-0.49

(-0.86,0.12)

Low frequency noise "pollution" interferes with performance

Persson, Waye K; Bengtsson, J; Kjellberg, A; Benton, S

2001

n = 32;

age mean: 23.3

The sound was produced by four loudspeakers, hidden behind curtains and placed in each comer of the room

To amplify the low frequency noise, there was a subwoofer (ace-bass B2-50) which can reproduce frequencies down to 20 Hz. The background noise from the test chamber ventilation was less than 22 dBA, and the sound pressure levels for frequencies below 160 Hz were below the threshold of normal hearing [ISO389-7:1996]

To obtain the low frequency noise, sound pressure

levels in the frequency region of 31.5 to 125 Hz

were increased using a digital sound processor

system

Memory

Short-time Memory Task

A set of numbers, e.g. 1 2 5 4, was shown on the computer screen. This set was followed by one number, e.g. 7. The subject was to respond, by yes or no, to whether that number was also present among the set of numbers shown earlier. The total response time and total number of correct and false answers were recorded

-0.26

(-0.38,0.20)

The Effect of Road Traffic Noise on Reaction Time

Alimohammadi, I; Zokaei, M; Sandrock, S

2015

n = 80; college students

At first stage the participants were asked to do the above mentioned RT test in the acoustic room in quiet condition (with background noise of 32.9 dBA) equipped with universal panel of Vienna test system. In second stage case group participants were exposed to traffic noise levels with 72.9 dBA for duration of two hours and then they did the RT test. In this stage, control group participants had been sat in acoustic room for two hours without noise and then they did RT test

In this experimental study, participants were exposed to road traffic noise with level of 72.9 dBA recorded and measured at ninety points in a central parts (that have often heavy traffic) of Tehran, Iran in 2012(31.5–500 Hz). Noise was measured at A– frequency weighting and fast time weighting. During the traffic noise measurement, the traffic noise was recorded by a high quality voice recorder

Attentional functioning

Reaction Time

(RT)

Reaction time was measured by RT test from Vienna Test System. Test form S5 was used in this study. This test form assess reaction time (split into reaction and motor time) in response to simple and complex visual or acoustic signals

0.46

(-0.02,0.90)

Executive functioning

Movement Time

The mechanical response movement consists either of two visual stimuli (yellow and red lights) or a visual and an acoustic stimulus (yellow light and tone at 2000 Hz). The respondents are instructed to respond less than 2 s otherwise the alternative signals are appeared. The time from the presentation stimuli on the monitor to taking index finger from golden button was considered as movement time

-0.06

(-0.50,0.38)

The effects of low frequency noise on mental performance and annoyance

Alimohammadi, Iraj; Sandrock, Stephan; Gohari, Mahmoud Reza

2013

n = 90; age mean: 23.46

After 30 min, subjects performed Stroop and Cognitrone tests again. During performing tests, there was LFN as well. In other words, the exposure duration to LFN was 30 min plus test performance time. For reducing recall bias, half of the subjects were exposed to 50 dBA at first, and the others were exposed to 70 dBA. At the beginning of each test, sound pressure level was measured near the head of the subject in octave band frequency by B&K (model 2238)

LFN in 50 and 70 dBAwas produced inside the acoustic room by Cool Edit Pro. 2.1. Some of the main sources LFN are computers, printers, and air conditioner systems, usually known as quiet devices. In many administrative offices, the Leq = 50 dB noise can be considered as quiet conditions Meanwhile, based on the authors experience, the noise level in the relatively crowded offices is around Leq = 70 dB

Attentional functioning

Cognitrone Test

Cognitrone test was used for evaluating attention and concentration via identical comparison of figures. In other words, Cognitrone test was applied to assess the attention and concentration through comparison of figures with regards to their congruence

-1.04

(-1.35, -0.73)

Executive functioning

Stroop Test

Stroop Interference Test is a sensorimotor speed test registering speed performance when reading words and naming colors and the speed performance under color–word interference conditions

-0.03

(-0.32,0.26)

The impact of low-frequency noise on human mental performance

Pawlaczyk-Luszczyniska, Malgorzata; Dudarewicz, Adam; Waszkowska, Malgorzata; Szymczak, Wieslaw; Sliwinska-Kowalska, Mariola

2005

n = 96;

age range:

19–27

Experiment was performed in a special chamber for

psychological tests (6.8 m²) furnished as an office environment. The preselected subjects, categorized in terms of individual sensitivity to LFN, performed standardized psychological tests during exposure to LFN or reference noise at the same equivalent-continuous A-weighted sound pressure level (SPL) of approx. 50 dB. Each subject carried out tasks once at randomly-assigned exposure conditions

The noise was generated by a set of loudspeakers placed in the corners of the room. Low frequency noise simulated noise occurring in the industrial control rooms. The reference noise was the broadband noise of a predominantly flat frequency character, without dominant low frequency components

Attentional functioning

The Continuous Attention Test (DAUF)

For thirty minutes, rows of triangles are presented on screen under time-critical conditions; the tips of the individual triangles can point either up or down. When a previously determined amount of triangles points down, the subject has to press the reaction button

-0.12

(-0.52,0.28)

Executive functioning

The Stroop Color-Word Test

It is based on the assumption that reading speed of a color-word is slower, if the word is written in a differently colored font. There is always a delay in naming the color of this word, if color and color-word do not match. This test is used for registration of the color-word interference tendency, i.e. impairment of the reading speed or color recognition due to interfering information. Therefore, it is useful in determining the individual susceptibility to stimulus disturbing mental processes

0.00

(-0.40,0.40)

Higher-order functions

The Comparing of Names Test

It consists of two columns of words (names). The respondent decides whether couples of words (names) in both columns are exactly the same. This test is designed to measure the ability to see pertinent detail in verbal material

-0.04

(-0.44,0.36)