This study investigated whether Mandarin lexical tones and hummed tones show different patterns of lateralization in dichotic listening. The study found that for hummed tones, participants performed better when attending to the left ear, showing a left ear advantage. However, for lexical tones there was no ear advantage, suggesting bilateral processing. Previous dichotic listening studies have found both left and right ear advantages for lexical tones. The current study is the first to show a left ear advantage for hummed Mandarin tones, reflecting right hemisphere processing. Attention effects were strongest when participants attended to one ear, consistent with previous dichotic listening research.

1. Dichotic Listening of Mandarin Tones: Hummed and Lexical Tone
Mei, N.1
,& Poeppel, D.1,3
, Tian, X.2
, Flinker, A.1
Psychology Department, New York University1
,Institute of Brain and Cognitive Science, NYU Shanghai, China2
,Max Planck Institute for Empirical Aesthetics, Frankfurt, Germany3
Introduction
• A right ear advantage (REA) is typically
reported when two competing syllables are
played to subjects. (Kimura, 1961)
• More accurate reports for the right ear
(REA) reflects left hemisphere dominant
processing.
• Studies of Mandarin and Thai tones
mostly report REA for lexical tones but
there are conflicting left ear advantage
(LEA) reports as well.(Van Lancker &
Fromin, 1973; Baudoin-Chial, 1986; Wang
et al., 2001, 2004)
Hypotheses
• Previous studies focused on
complex vowels (ao) while we are
examining simple vowels (i)
• Most studies examined only lexical
tones while we are comparing both
lexical and hummed tones.
• Lexical and hummed tones engage
different cortical auditory
processes.
• H1:Hummed tones will produce a
LEFT ear behavioral advantage
engaging right hemisphere
processing.
• H2: Lexical tones will produce a
RIGHT ear behavioral advantage
engaging left hemisphere
processing.
Design
24 (15 females,9 males) Mandarin speaking under-
graduates were recruited from NYU Shanghai cam-
pus. 4 of them were excluded due to over 5 db differ-
ence in hearing threshold of both ears.
• Within subject design.
• IV1:hummed tones and simple tones; IV2:
attention to: 1)both ears, 2) left ear; 3) right ear.
• Stimuli were natural speech utterances recorded
from a female Mandarin speaker.
The materials used in the experiment are
outlined below:
1 Hummed tones: hum1
, hum2
, hum3
, hum4
,
Duration is 306 ms.
2 Lexical tones: i1
, i2
, i3
, i4
, Duration is 323 ms.
Methods
• Audiometer hearing threshold testing
• Main Experiment is divided to 2
conditions: hummed and simple tone.
Order of the 2 conditions are randomized.
• Within each condition, there are 3 blocks
of main tasks:
• Block 1: pay attention to both ears
equally.
• Block 2: pay attention to one of the ears.
• Block 3: pay attention to the other ear.
During the tasks, participants were asked to
press ’1’,’2’,’3’,’4’ for the tone they thought
they heard first.
Hummed tones - LEA
Figure 1: Within Subject Performance in Hummed Condition
• Gender and response hands are
counterbalanced.
• There is a significant difference between
proportion of correct responses from left
and right ears, when participants paid
attention to both ears equally. t(40)=3.04,
p<.01.
Lexical tones - no preference
Figure 2: Within Subject Performance in Simple Tone Condition
• There is no significant difference between
the proportion of correct responses from
left and right ears, when participants paid
attention to both ears equally. t(40)=0.27,
p>.05.
Individual performance
Figure 3: Distribution of Individual Performance
• The yellow quadrant represents poor
performers.
• The light blue quadrant represents a
greater REA.
• The purple quadrant represent a greater
LEA.
Conclusion
• For the first time in Mandarin hummed
tones, we show a LEA reflecting right
hemisphere processing.
• The processing of lexical tones might be
bilateral.
• Attention effects in the control conditions
are the strongest, consistent with dichotic
listening literature.
Future Research Direction
• Investigate lexical (semantic) effects in
real- and pseudo- Mandarin words.