Turn Off the White Noise Immediately…Well Maybe Not!
A recent review in JAMA Otolaryngology-Head & Neck Surgery discusses potential negative unintended consequences of broadband noise (BBN) for tinnitus therapy. Attarha et al (2018) present an argument suggesting that data demonstrating influence of BBN on maladaptive plasticity in the auditory pathway may further impair central function and result in a net increase in neural activity (or loss of inhibition) related to tinnitus perception. The manuscript then goes on to discuss novel neuroplasticity-based approaches, including BrainHQ, an adaptive computerized auditory training program developed by the senior author (Merzenich).
The arguments to support their logic suffers from two fundamental flaws. First, the application of BBN in management of tinnitus is not intended to treat tinnitus or engage neural plasticity to disrupt the tinnitus signal. The common application of BBN in tinnitus management is to either “mask” or partially reduce tinnitus perception to aid in the habituation process, i.e., treat the reaction to the tinnitus, not to create neural plasticity to disrupt the signal. Second, the data demonstrating the effect of BBN in creating impaired central auditory function is limited primarily to rodent experiments, where animals are exposed to low level BBN for extended durations of time without other stimulation (e.g., Zhou and Merzenich 2012). However, BBN does not turn off subsequent plasticity that may occur (e.g., Zhu et al, 2014); otherwise BrainHQ would be ineffective. Humans are not raised in BBN in the absence of complex sounds such as speech, music, etc. Therefore, the implications of BBN creating substantial negative consequences on cortical function in humans is largely unknown and likely minimal with exposure to non-BBN sounds.
The suggestion that BBN is not an effective signal to engage neuroplasticity to treat tinnitus is fairly well supported by the authors and a summary on novel developments in tinnitus plasticity-based approaches is provided. The limitation of these studies thus far is lack of placebo-controlled randomized trials and comparison to common tinnitus management strategies. These developments are encouraging, but at this point, none have shown to cure tinnitus. The evidence that BBN exacerbates tinnitus in the majority of patients is at this time unsupported and would be contrary to a fairly substantial literature on the effectiveness of masking and sound therapy approaches for tinnitus management.
Attarha M, Bigelow J, Merzenich M. (2018) Unintended consequences of white noise therapy for tinnitus-Otolaryngology’s Cobra Effect. JAMA Otolaryngol, prepub.
Zhou X, Merzenich M. (2012) Environmental noise exposure degraded normal listening processes. Nat Comm 3: 843.
Zhu X et al. (2014) Environmental acoustic enrichment promotes recovery from developmentally degraded auditory cortical processing. J Neurosci 34 (16):5406–5415.