White Noise

White noise (white noise), is a stationary sound spectrum formed by the equal intensity, continuous, and random combination of all frequencies between 20 Hz and 20,000 Hz that the human ear can perceive. By its physical nature, this sound composition exhibits a monotonous structure and derives its name from optical science: just as white light contains all colors of the spectrum, white noise encompasses all audible sound frequencies.^【1】

The primary function of white noise is defined as "auditory masking". This mechanism impedes or prevents the brain from perceiving sudden and sharp changes in ambient sounds—such as door slams or voices—by establishing a constant auditory background threshold. Due to this property, white noise serves as a protective barrier in environments with high levels of noise pollution, such as hospitals or offices, helping to maintain focus and improve sleep quality.^【2】

White noise effectively aids in filtering external stimuli by influencing the reticular activating system in the brain. Electroencephalography (EEG) studies have demonstrated that exposure to white noise induces specific changes in brain wave patterns:

Low-Frequency Waves: In subjects exposed to white noise, increases in theta waves (4–8 Hz), particularly in the frontal region, and delta waves (1–4 Hz) across the overall spectrum have been observed. This is associated with deep relaxation and activation of the parasympathetic nervous system.^【3】

Alpha Waves and Anxiety: The observed increase in alpha waves, which reflect mental balance and calmness, contributes to reduced stress levels and decreased anxiety.^【4】

• Anesthesia and Surgical Procedures: The sounds of medical equipment and staff conversations in operating rooms can induce high levels of anxiety in patients. Administering white noise to patients under regional anesthesia reduces these disturbing noises, enhancing sedation levels and postoperative satisfaction.^【5】
• Neonatal and Infant Care: White noise mimics the intrauterine sound environment. Its similarity to maternal sounds such as blood flow and gastric noises creates a reassuring space that infants do not perceive as foreign.^【6】
• • Feeding and Sucking Success: The positive effects of white noise on neonatal sucking success and feeding stabilization have been confirmed using clinical assessment scales such as LATCH.^【7】
  • Pain Management: Infants exposed to white noise during invasive procedures such as heel sticks show reduced pain scores and shorter crying durations.^【8】
• Noise Colors and Variants: In addition to white noise, other types such as "pink noise" (pink noise) and "brown noise" (brown noise) are documented in the literature, differentiated by their frequency intensity profiles. Pink noise exhibits higher energy at lower frequencies, producing a softer acoustic character, while brown noise has a much deeper and bass-heavy structure.^【9】