Wireless sensor networks have recently gained a lot of attention from the research community. Wireless sensor networks are often partitioned into clusters, each managed by a cluster head (gateway). In this paper, we study the performance of the IEEE 802.11 based wireless sensor networks in noisy environments. We show that using the standard binary exponential backoff (BEB) mechanism in noisy clustered sensor networks results in a poor throughput performance due to its inability of differentiating between the causes of unsuccessful packet transmissions and verify the analytical model using the ns-2 simulator. We show the enhanced BEB mechanism in [T. Nadeem et al. (2004)] enhances clustered sensor network performance up to order of magnitudes with respect to the network error rates (noise level). We also study the noise effect on the fairness of IEEE 802.11 and show that our proposed mechanism maintains the channel fairness between the competing sensors.