Design and a notch filter using two Butterworth filters in parallel (MATLAB) I am doing a project to filter out a 1kHz noise inserted to a 30sec .wav audio file. 
To filter out the 1kHz noise, I am required to design using two Butterworth filters connected in parallel where one is a low pass and the other is a high pass Butterworth Filter. 

I have tried to notch out the 1kHz noise by setting the bandwidth to (+/-10Hz) of the 1kHz noise. 
Therefore, the range of the noise signal to be attenuated will be from 990Hz to 1010Hz. 

I am planning to obtain the transfer function in s-domain first and then transform it to z-domain. 

The designed transfer function will be inputted into MATLAB and the filtered audio file will be obtained. 

May I know the steps in designing this filter? Cost-effectiveness and ease of implementation of the filter is emphasised. 

Thanks.
Cost-effectiveness and ease of implementation of the filter is emphasised.


It that's a your goal then you really shouldn't be using two Butterworth filters. Use a notch filter instead. If there is a "requirement" to use other filters, please explain why this is required. I think your best bet here is to change the requirement.