The perception of a persistent, deep sound, often described as hearing “bass” in the ear, is a specific form of tinnitus. Tinnitus is the experience of hearing sound when no external source is present. While commonly known as a high-pitched ringing, it can manifest as a low-frequency hum, throbbing, or deep rumbling sound. This low-pitched version is generally considered subjective, meaning only the individual can hear it. Understanding the source of this internal sound requires examining the mechanics of the ear, the body’s circulatory system, and the neurological processing of sound.
Anatomical Causes and Pressure
Physical blockages or pressure imbalances within the ear structure are frequent causes of low-frequency sounds. The outer ear canal can become blocked by excessive cerumen, or earwax, which creates a muffled sensation and amplifies internal body sounds, leading to a rumbling perception. This blockage changes the air pressure dynamics in the ear, causing the eardrum to vibrate differently.
Issues in the middle ear, the air-filled space behind the eardrum, are also common contributors to this bass-like sound. The Eustachian tube, which connects the middle ear to the back of the throat, is responsible for equalizing air pressure. When this tube becomes dysfunctional—often due to allergies, a cold, or infection—it causes a pressure imbalance. This imbalance can result in a feeling of fullness, muffled hearing, and a low-frequency noise described as thumping or roaring. Fluid buildup from an ear infection similarly restricts the eardrum’s movement, emphasizing lower frequencies of internal noise.
Vascular Sources and Pulsatile Sounds
A distinct type of low-frequency noise is pulsatile tinnitus, characterized by a rhythmic sound synchronized with the individual’s heartbeat. This sound is generated by turbulent blood flow in vessels located near the ear structures. Unlike most subjective tinnitus, pulsatile tinnitus can sometimes be heard by a doctor during an examination, classifying it as objective tinnitus.
Conditions that increase the force or volume of blood flow are often the underlying source of this rhythmic sound. High blood pressure or atherosclerosis can force blood to move with increased intensity, creating a rushing or whooshing noise near the inner ear’s delicate structures. Vascular abnormalities, such as a narrowing of a large vein like venous sinus stenosis, can also disrupt normal flow, leading to this pulse-synchronous sound.
Neural Response and Hearing Damage
The perception of a low-frequency hum can also be a neurological phenomenon resulting from damage to the inner ear. Sensorineural tinnitus occurs when the delicate hair cells within the cochlea are damaged. While high-pitched ringing is the most common manifestation, damage to the hair cells responsible for low-frequency sound perception can result in a phantom low-pitched drone.
When the brain receives reduced sensory input from the damaged cochlea, it attempts to compensate for the missing information. This compensation involves an increase in neural activity, often referred to as “increased central gain,” within the auditory processing centers of the brain. The brain effectively generates a persistent, perceived sound to fill the silence. This may manifest as a deep hum if the low-frequency hair cells were specifically affected by noise exposure or age-related hearing loss. Prolonged exposure to strong, sustained low-frequency vibrations can contribute to this specific type of inner ear damage.
Determining When to Seek Help
While many cases of low-frequency tinnitus are temporary, certain symptoms warrant a prompt consultation with a physician or audiologist. Seek evaluation if the bass sound occurs in only one ear, as unilateral tinnitus can signal a more serious underlying issue. The presence of accompanying symptoms should also prompt a medical visit.
- Sudden hearing loss.
- Severe dizziness or vertigo.
- Persistent ear pain.
- The sound is strongly pulsatile (beating in time with your pulse).
- The sound significantly interferes with sleep, concentration, or quality of life.