Academic journal article Journal of Medical Speech - Language Pathology

The Effect of Background Noise on the Speech Intensity of Individuals with Hypophonia Associated with Parkinson's Disease

Academic journal article Journal of Medical Speech - Language Pathology

The Effect of Background Noise on the Speech Intensity of Individuals with Hypophonia Associated with Parkinson's Disease

Article excerpt

Keywords: Parkinson's disease, hypophonia, speech intensity, Lombard effect

Reduced speech intensity or hypophonia often is a consequence of hypokinetic dysarthria associated with Parkinson's disease (PD). Because the impact of hypophonia often is exacerbated in noise, the introduction of background noise during conversational tasks is a particularly relevant context in which to study this speech symptom. The purpose of this study was to examine the effect of background noise on the speech intensity of 30 participants with hypophonia associated with PD and 15 control participants. Measures of maximum speech intensity and habitual conversational speech intensity were obtained for both groups. Conversational speech intensity was measured in various intensity levels of background noise in both groups. Results revealed significant differences between groups in maximum speech intensity, habitual conversational speech intensity, and conversational speech intensity in background noise. Specifically, participants with PD were significantly less intense (by -5 dB sound pressure level [SPLA) than control participants in various intensity levels of background noise. Furthermore, participants with PD demonstrated a similar but attenuated pattern of response to the various intensity levels of background noise. This suggests that a potentially important and fundamental aspect of hypophonia in PD may be the lack of ability to accurately regulate speech intensity relative to background noise conditions.

INTRODUCTION

One of the most disabling aspects of Parkinson's disease (PD) is its effect on spoken communication. It is estimated that more than 75% of individuals with PD will present with speech and voice abnormalities related directly to PD (Logemann, Fisher, Boshes, & Blonsky, 1978; Sapir, Ramig, Hoyt, Countryman, O'Brien, & Hoehn, 2002). Reduced speech intensity, or hypophonia, often is a consequence of hypokinetic dysarthria associated with PD. Hypophonia can be a disabling aspect of hypokinetic dysarthria and a frustrating experience for speakers with PD.

Hypophonia Associated with Hypokinetic Dysarthria

Although not originally described as a distinctive feature in Darley, Aronson, and Brown's (1969) clinical characterization of hypokinetic dysarthria, hypophonia often emerges as an initial speech symptom in the beginning stages of PD (Logemann et al., 1978) but it is not present in all individuals with hypokinetic dysarthria. Ludlow and Bassich (1984) and Gamboa et al. (1997) found that hypophonia was present in 42% and 49% of individuals they studied with hypokinetic dysarthria, respectively. Anecdotally, there are reports that individuals with PD often complain that others ask for them to speak louder and to repeat themselves, and communication partners indicate the individuals with hypophonia often lack an awareness of their softer voice or reduced loudness (Adams & Dykstra, 2008; Dromey & Adams, 2000; Duffy, 1995; Ramig, 1998). Although reduced loudness is a salient perceptual characteristic in individuals with PD (Darley, Aronson, & Brown, 1975; Logemann et al., 1978), there are inconsistencies in acoustic evidence for this claim. Illes, Metter, Hanson, and Iritani (1988) demonstrated reduced loudness in individuals with PD during a reading task. There also is a small but emerging literature that has confirmed reduced speech intensity levels in speakers with PD during conversational tasks (Ho, Iansek, & Bradshaw, 1999; Moon, 2005) and monologues (Fox & Ramig, 1997). In general, however, few studies have been able to find significant acoustic differences in speech intensity between individuals with PD and healthy age-matched control participants (Canter, 1963; Kempler & Van Lancker, 2002; Metter & Hanson, 1986).

There appears to be dichotomy between clinical, perceptual impressions of hypophonia in PD and the instrumental or acoustic measures that often fail to capture this perceptual speech feature. …

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