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Letters to the Editor
June 2012

Potential Errors in Phonatory Results

Author Affiliations

Author Affiliations: Department of Otolaryngology, Far Eastern Memorial Hospital, Taipei, Taiwan.

Arch Otolaryngol Head Neck Surg. 2012;138(6):608. doi:10.1001/archoto.2012.904

We read with great interest the article titled “Local Steroid Injection via the Cricothyroid Membrane in Patients With a Vocal Nodule” by Lee et al.1 In this article, the authors demonstrated the clinical usefulness of vocal fold steroid injection in 80 patients with vocal nodules. The treatment outcomes were quite satisfactory: the nodules disappeared in 44% of the patients and improved in 49%. Subjective assessment using a voice handicapped index also showed a significant improvement in each of the 3 domains. Also, the authors reported significant improvements between the preoperative and the postoperative phonatory results, including jitter, shimmer, noise to harmony ratio (NHR), average fundamental frequency, and maximum phonation time. However, on closer inspection, there were potentially incorrect data. First, because the NHR represents a fraction of noise energy over harmonic energy, it is unlikely to result in a value greater than 1. According to the normative data provided in the multidimensional voice program,2 the mean (SD) of the NHR was 0.112 (0.009) and 0.122 (0.014) for female and male patients, respectively. Similarly, the reported data for the mean (SD) shimmer were unusually low when compared with the normative data from the multidimensional voice program: 1.997 (0.791) for female patients and 2.523 (0.997) for male patients. Interestingly, when the data for the shimmer and the NHR are substituted for one another, the results seem more reasonable and closer to what we usually get from an acoustic analysis. Therefore, we recommend that the authors take another look at the original data and correct any mistakes in the phonatory results that might have occurred.